Lithographic printing plate precursor, method of producing same, and printing method using same

ABSTRACT

Provided are a lithographic printing plate precursor for furnishing a lithographic printing plate in which adhesion to interleaving paper is prevented, contamination inside a device is prevented, and edge stain does not occur; a method of producing the same; and a printing method using the same. The lithographic printing plate precursor includes: a support; and an image recording layer on the support, in which a region of a surface of the lithographic printing plate precursor at a side of the image recording layer, which is from an end portion of the lithographic printing plate precursor to a portion inside the end portion by 5 mm, contains at least-one polymer selected from polyamide, polyurethane, polyurea, polyester and polycarbonate, and has a content of the polymer per unit area which is greater than a content of the polymer per unit area in a region other than the above-described region by an amount of 10 mg/m 2  or greater.

CROSS REFERENCE TO RELATED APPLICATION

This is a Continuation of U.S. application Ser. No. 15/661,175, filedJul. 27, 2017, which is a continuation of International Application No.PCT/JP2016/052188 filed on Jan. 26, 2016, and claims priority fromJapanese Patent Application No. 2015-015962 filed on Jan. 29, 2015, theentire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a lithographic printing plateprecursor, a method of producing the same, and a printing method usingthe same.

2. Description of the Related Art

Currently, in preparation of a lithographic printing plate, imageexposure has been performed using a computer-to-plate (CTP) technology.That is, the image exposure is performed by directly scanning andexposing a lithographic printing plate precursor using a laser or alaser diode without using a lith film. Along with this, objects of alithographic printing plate precursor have been changed to improvementof image-forming characteristics, printing characteristics, and physicalproperties corresponding to the CTP technology.

From the growing interest in the global environment, environmentalproblems related to a waste liquid associated with wet treatments suchas a development treatment have been closed up as a problem of alithographic printing plate precursor. Along with this, it is desired tosimplify a development treatment or not to perform a developmenttreatment. As one of a simple development treatment, a method referredto as “on-press development” has been suggested. In other words, theon-press development is a method of exposing a lithographic printingplate precursor, mounting the lithographic printing plate precursor on aprinting press without performing a development treatment of the relatedart, and then removing an unnecessary portion of an image recordinglayer, at an initial stage of a typical printing step.

In a case where printing is performed using a lithographic printingplate, since the end portions of the printing plate are in positionsother than paper at the time of printing on paper press, the endportions do not affect the print quality. However, in a case whereprinting is continuously performed on roll-like paper using a rotarypress during newspaper printing or the like, since the end portions ofthe printing plate are on the surface of rolled paper, the ink adheringto the end portions is transferred to the paper and forms linear stain(hereinafter, also referred to as edge stain) and thus the commodityvalue of the printed matter is significantly impaired.

As a method of preventing edge stain on an on-press development typelithographic printing plate precursor, a method of performing atreatment on a region within 1 cm from the end portions of the on-pressdevelopment type lithographic printing plate precursor for printingnewspaper with a solution containing an organic solvent and ahydrophilic resin or a treatment solution containing an anionic ornon-ionic surfactant has been suggested (see JP2011-177983A andJP2014-104631A).

SUMMARY OF THE INVENTION

However, according to the technologies described in JP2011-177983A andJP2014-104631A, it was found that a treated region occasionally adheresto the interleaving paper in contact with the treated region in a casewhere lithographic printing plate precursors treated with a treatmentsolution are stored in a stacked state by interposing interleaving papertherebetween even though the problem of edge stain can be solved to someextent. Therefore, a problem in that the interleaving paper is unlikelyto be peeled off from the lithographic printing plate precursor in asetter during an exposing step of the lithographic printing plateprecursor occurs. Further, it was found that the portion treated withthe treatment solution is transferred to a conveyance path and led tocontamination inside a device such as a setter or a punch bender in aseries of plate production processes from the exposure to the print oflithographic printing plates.

An object of the present invention is to provide a lithographic printingplate precursor for furnishing a lithographic printing plate in whichadhesion to interleaving paper is prevented, contamination inside adevice is prevented, and edge stain does not occur; a method ofproducing the same; and a printing method using the same.

(1) A lithographic printing plate precursor comprising: a support; andan image recording layer on the support, in which a region of a surfaceof the lithographic printing plate precursor at a side of the imagerecording layer, which is from an end portion of the lithographicprinting plate precursor to a portion inside the end portion by 5 mm,contains at least one polymer selected from polyamide, polyurethane,polyurea, polyester and polycarbonate, and has a content of the polymerper unit area which is greater than a content of the polymer per unitarea in a region other than the above-described region by an amount of10 mg/m² or greater.

(2) The lithographic printing plate precursor according to (1), in whichthe polymer includes at least one group selected from a carboxy group, asulfo group, a phosphoric acid group, a phosphonic acid group, asulfuric acid group, an amino group, and a polyalkylene oxide group.

(3) The lithographic printing plate precursor according to (1) or (2),in which the end portion of the lithographic printing plate precursorhas a shear drop shape in which an amount X of shear drop is in a rangeof 35 to 150 μm and a width Y of shear drop is in a range of 70 to 300μm.

(4) The lithographic printing plate precursor according to any one of(1) to (3), in which the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and a binder polymer.

(5) The lithographic printing plate precursor according to any one of(1) to (3), in which the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and a polymer compound having a fine particle shape.

(6) The lithographic printing plate precursor according to any one of(1) to (3), in which the image recording layer contains an infraredabsorbing agent and a thermoplastic polymer fine particles.

(7) A method of producing a lithographic printing plate precursor whichincludes a support; and an image recording layer on the support, inwhich a region of a surface of the lithographic printing plate precursorat a side of the image recording layer, which is from an end portion ofthe lithographic printing plate precursor to a portion inside the endportion by 5 mm, contains at least one polymer selected from polyamide,polyurethane, polyurea, polyester and polycarbonate, and has a contentof the polymer per unit area which is greater than a content of thepolymer per unit area in a region other than the above-described regionby an amount of 10 mg/m² or greater, the method comprising: an imagerecording layer forming step a of forming the image recording layer; acoating step b of coating a region of a part of the image recordinglayer which is formed by the step a with a coating solution containingthe polymer such that the coating solution and the region overlap eachother; and a cutting step c of cutting the region coated with thecoating solution such that the region of a surface of the lithographicprinting plate precursor at a side of the image recording layer is in arange from the end portion of the cut lithographic printing plateprecursor to a portion inside the end portion by 5 mm, in which thesteps are performed in order of the step a, the step b, and the step cor in order of the step b, the step a, and the step c, on the support.

(8) The method of producing a lithographic printing plate precursoraccording to (7), in which an undercoat layer forming step d of formingan undercoat layer is performed on the support before the step a.

(9) The method of producing a lithographic printing plate precursoraccording to (7) or (8), in which a protective layer forming step e offorming a protective layer is performed on the image recording layerafter the step a and before the step c.

(10) A method of producing a lithographic printing plate precursor whichincludes a support; and an image recording layer on the support, inwhich a region of a surface of the lithographic printing plate precursorat a side of the image recording layer, which is from an end portion ofthe lithographic printing plate precursor to a portion inside the endportion by 5 mm, contains at least one polymer selected from polyamide,polyurethane, polyurea, polyester and polycarbonate, and has a contentof the polymer per unit area which is greater than a content of thepolymer per unit area in a region other than the above-described regionby an amount of 10 mg/m² or greater, the method comprising: an imagerecording layer forming step a of forming the image recording layer; anda coating step f of coating a region of a surface of the lithographicprinting plate precursor at a side of the image recording layer, whichis from the end portion of the lithographic printing plate precursor toa portion inside the end portion by 5 mm, with a coating solutioncontaining the polymer, in which the steps are performed in order of thestep a and the step f on the support.

(11) The method of producing a lithographic printing plate precursoraccording to (10), in which an undercoat layer forming step d of formingan undercoat layer is performed on the support before the step a.

(12) The method of producing a lithographic printing plate precursoraccording to (10) or (11), in which a protective layer forming step e offorming a protective layer is performed on the image recording layerafter the step a and before the step f.

(13) The method of producing a lithographic printing plate precursoraccording to any one of (7) to (12), in which the polymer includes atleast one group selected from a carboxy group, a sulfo group, aphosphoric acid group, a phosphonic acid group, a sulfuric acid group,an amino group, and a polyalkylene oxide group.

(14) A lithographic printing plate precursor which is obtained by theproduction method according to any one of (7) to (13).

(15) A printing method comprising: image-exposing the lithographicprinting plate precursor according to any one of (1) to (6) and (14);and supplying printing ink and dampening water to remove an unexposedportion of the image recording layer and performing printing on aprinting press.

(16) The printing method according to (15), in which the printing isperformed using printing paper having a width wider than the width ofthe lithographic printing plate precursor.

According to the present invention, it is possible to provide alithographic printing plate precursor for furnishing a lithographicprinting plate in which adhesion to interleaving paper is prevented,contamination inside a device is prevented, and edge stain does notoccur; a method of producing the same; and a printing method using thesame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a cross-sectional shape of anend portion of a cut lithographic printing plate precursor.

FIG. 2 is a conceptual view illustrating an example of a cutting portionof a slitter device.

FIG. 3 is a side view illustrating the concept of a brush graining stepused for a mechanical roughening treatment in production of a supportfor a lithographic printing plate.

FIG. 4 is a side view illustrating an example of a radial type cell usedfor an electrochemical roughening treatment for which an alternatingcurrent is used in production of a support for a lithographic printingplate.

FIG. 5 is a schematic view illustrating an anodizing treatment deviceused for an anodizing treatment in production of a support for alithographic printing plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail.

A lithographic printing plate precursor of the present inventionincludes a support; and an image recording layer on the support, inwhich a region on the plate surface on the image recording layer side (aregion of a surface of the lithographic printing plate precursor at aside of the image recording layer), which is from an end portion of thelithographic printing plate precursor to a portion inside the endportion by 5 mm, contains at least one polymer (hereinafter, alsoreferred to as a specific polymer) selected from polyamide,polyurethane, polyurea, polyester and polycarbonate, and has a contentof the polymer per unit area which is greater than a content of thepolymer per unit area in a region other than the above-described regionby an amount of 10 mg/m² or greater.

In a lithographic printing plate precursor of the related art, it isknown that constituent layers thereof such as an undercoat layer (alsoreferred to as an interlayer), an image recording layer (also referredto as an image-forming layer), and a protective layer (also referred toas an overcoat layer) contain a specific polymer. However, in all casesof these layers, the polymer is substantially uniformly present in theplane of the constituent layer of the lithographic printing plateprecursor. That is, there is substantially no difference between thecontent of the polymer in the central portion and the content of thepolymer in an end portion of the lithographic printing plate precursor.

Meanwhile, in the lithographic printing plate precursor of the presentinvention, the content of the specific polymer in end portion regions isintentionally set to be greater than the content of the specific polymerin regions other than the end portion regions by means of coating onlythe end portion regions of the lithographic printing plate precursorwith a coating solution containing the specific polymer. Specifically,the content of the specific polymer per unit area in a region on theplate surface on the image recording layer side from the end portion ofthe lithographic printing plate precursor to a portion inside the endportion by 5 mm is greater than the content of the specific polymer perunit area in a region other than the region by an amount of 10 mg/m² orgreater. When a difference between the content of the specific polymerper unit area in a region on the plate surface on the image recordinglayer side from the end portion of the lithographic printing plateprecursor to a portion inside the end portion by 5 mm and the content ofthe specific polymer per unit area in a region other than the region isspecified as described above, a lithographic printing plate precursorfor furnishing a lithographic printing plate in which adhesion tointerleaving paper is prevented, contamination inside a device isprevented, and edge stain does not occur is obtained.

The difference between contents of the specific polymer is preferably ina range of 10 to 5000 mg/m², more preferably in a range of 30 to 3000mg/m², and particularly preferably in a range of 50 to 1000 mg/m².

Here, the end portions of the lithographic printing plate precursorindicate edge portions to be formed by a step of cutting in a sheetshape during the step of producing a lithographic printing plateprecursor. A sheet-like lithographic printing plate precursor has fourend portions vertically and horizontally. From the viewpoint ofpreventing edge stain, the number of end portions with a high content ofthe specific polymer according to the present invention is 1 to 4 inrelation to the size of printing paper. For example, in a case ofprinting newspaper, two facing sides of the lithographic printing plateprecursor within the plane of printing paper along the roll paperconveyance direction typically correspond to the end portions.

The region on the plate surface on the image recording layer side fromthe end portion to a portion inside the end portion by 5 mm includes notonly the image recording layer but also all layers provided on the imagerecording layer side of a support. Accordingly, the content of thespecific polymer per unit area in the region on the plate surface on theimage recording layer side from the end portion to a portion inside theend portion by 5 mm indicates the total content of the specific polymerpresent on the region from the end portion on the image recording layerside of the lithographic printing plate precursor to a portion insidethe end portion of the lithographic printing plate precursor by 5 mm,per unit area. Similarly, the content of the specific polymer in aregion other than the region per unit area indicates the total contentof the specific polymer present in the region per unit area.

Hereinafter, in the lithographic printing plate precursor of the presentinvention, the region on the plate surface on the image recording layerside from the end portion to a portion inside the end portion by 5 mm isalso referred to as an end portion region. Further, the region on theplate surface on the image recording layer side other than the endportion region is also referred to as the other region.

The content of the specific polymer in the end portion region and theregion other than the end portion region per unit area can be measuredusing the infrared absorption spectrum. The measurement method using theinfrared absorption spectrum is not particularly limited, but amicroscopic reflection method is preferable. It is preferable that thespectrum to be obtained is a Fourier transform spectrum. The measurementis performed in the following manner by assuming that the specificpolymer is polyurethane.

Samples corresponding to the end portion region and the region otherthan the end portion region of the lithographic printing plate precursorare prepared and the Fourier transform infrared absorption spectrum(FT-IR) of the coating film of each sample on the support is measured(device: Nicolet Avater 320 FT-IR (manufactured by Thermo FisherScientific, measurement method: microscopic reflection method,measurement wavenumber range: approximately 4000 to 900 cm⁻¹,resolution: 4 cm⁻¹, number of times of integration: 128 times). A peakintensity difference (Xa) based on C═O stretching vibration derived froma urethane bond is acquired from a difference in spectrum between thetwo samples. Separately, samples obtained by changing the coatingamounts of polyurethane into 10, 100, and 1000 mg/m² are prepared, andthe peak intensity (X) (peak based on C═O stretching vibration derivedfrom a urethane bond: 1740 to 1690 cm⁻¹) in each coating amount ismeasured in the same manner. The calibration curve of the coating amount(mg/m²) with respect to the peak intensity (X) is created and aninclination (A) thereof is acquired. A difference in content ofpolyurethane between the end portion region and the region other thanthe end portion region per unit area is calculated according to thefollowing equation using the peak intensity difference (Xa) and theinclination of the calibration curve (A).

Difference in content of polyurethane per unit area (mg/m²)=(A)×(Xa)

In a specific polymer other than polyurethane, a difference in contentof the specific polymer can be acquired, in the same manner as describedabove, by measuring the specific peak intensity derived from a bond ineach of the following polymers.

Polyamide: 1680 to 1630 cm⁻¹ (C═O stretching vibration)

Polyurea: 1640 to 1610 cm⁻¹ (C═O stretching vibration)

Polyester: 1750 to 1720 cm⁻¹ (C═O stretching vibration), 1210 to 1120cm⁻¹ (C═O stretching vibration)

Polycarbonate: 1780 to 1750 cm⁻¹ (C═O stretching vibration)

[Specific Polymer]

The polyamide, polyurethane, polyurea, polyester, and polycarbonatewhich are specific polymers contained in the end portion region of thelithographic printing plate precursor according to the present inventionwill be described below.

[Polyamide]

The polyamide includes polymers having an amide bond (—NRC(═O)— (here, Rrepresents a hydrogen atom or a substituent)) in the main chain or thegraft chain and derivatives thereof. It is preferable that the mainchain has an amide bond.

The polyamide is basically synthesized through a co-condensationpolymerization reaction between a diamine compound and a dicarboxylicacid compound (alternatively, a dicarboxylic acid chloride), apolycondensation reaction of amino acid, or ring-opening polymerizationof a lactam. For example, the polyamide can be synthesized using themethod described in Experimental Chemistry Course, 4th edition, Vol. 28,polymer synthesis, pp. 252 and methods in conformity with this method.

Examples of the diamine compound include p-phenylenediamine,m-phenylenediamine, 2,5-diaminotoluene, 2,5-diaminophenol,3,5-diaminobenzyl alcohol, 4,4′-diaminobiphenyl,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 4,4′-sulfonyldianiline, 4,4′-diaminodiphenylamine, 4,4′-diaminobenzophenone,1,4-diaminonaphthalene, 1,2-bis(4-aminophenyl)ethane,1,4-bis(4-aminophenyl)butane, 1,3-bis(4-aminophenyl)benzene,1,4-bis(4-aminobenzyl)benzene, 1,3-diaminopropane, 1,4-diaminobutane,1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane,1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane,1,11-diaminoundecane, and 1,12-diaminododecane.

Examples of the dicarboxylic acid compound include oxalic acid, malonicacid, succinic acid, glutaric acid, adipic acid, pimelic acid, subericacid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid,1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid,terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,fumaric acid, maleic acid, 1,3-benenediacetic acid, and1,4-benenediacetic acid.

Examples of the amino acid include ε-aminocaproic acid, glutamic acid,aspartic acid, lysine, arginine, histidine, glycine, alanine, leucine,serine, cysteine, glutamine, asparagine, phenylalanine, and tyrosine.

Examples of the lactam include s-caprolactam, undecane lactam, andlauryl lactam.

Preferred examples of the polyamide include a polyamide having a sulfogroup or a sulfonyl group in the side chain thereof described inJP1973-72250A (JP-S48-72250A), a polyamide having an ether bond or apolyether bond in the main chain or in the side chain thereof describedin JP1974-43465A (JP-S49-43465A) or JP1980-74537A (JP-S-55-74537A), anda polyamide having an amino group in the main chain or in the side chainthereof described in JP1975-7605A (JP-S-50-7605A). Further, commerciallyavailable products such as AQ NYLON (manufactured by Toray Co., Ltd.)can be used.

Derivatives of the polyamide include compounds in which atoms in apolyamide molecule are substituted or the structure of an amide bond ischanged due to an addition reaction, for example, a compound obtained bysubstituting a hydrogen atom of an amide bond with a methoxymethyl groupusing a polyamide as a raw material.

[Polyurethane]

The polyurethane includes polymers having a urethane bond (—NRC(═O)O—(here, R represents a hydrogen atom or a substituent)) in the main chainor the graft chain and derivatives thereof. It is preferable that themain chain has a urethane bond.

The polyurethane is basically synthesized through a condensationreaction between a diisocyanate compound and a diol compound.

Examples of the diisocyanate compound include an alicyclic diisocyanatecompound such as hexamethylene diisocyanate,2,2,4-trimethylhexamethylene diisocyanate, hydrogenated xylylenediisocyanate, 1,4-cyclohexane diisocyanate, or 4,4-dicyclohexylmethanediisocyanate; an araliphatic diisocyanate compound such as xylylenediisocyanate or tetramethylxylylene diisocyanate; an aromaticdiisocyanate compound such as toluylene diisocyanate or phenylmethanediisocyanate; and modified products of these diisocyanates (such as acarbodiimide-containing modified product, a uretdione-containingmodified product, and a uretoimine-containing modified product).

Examples of the diol compound include a diol compound obtained by(co)polymerizing alkylene oxide such as ethylene oxide or propyleneoxide or heterocyclic ether such as tetrahydrofuran. Specific examplesof the diol compound include polyether diol such as polyethylene glycol,polypropylene glycol, polytetramethylene ether glycol, orpolyhexamethylene ether glycol; polyester diol such as polyethyleneadipate, polybutylene adipate, polyneopentyl adipate,poly-3-methylpentyl adipate, polyethylene/butylene adipate, orpolyneopentyl/hexyl adipate; polylactone diol such as polycaprolactonediol; and polycarbonate diol. Among these, polyether-based compounds,polyester-based compounds, and polycarbonate-based compounds arepreferable. Further, a diol compound having an acid group such as acarboxylic acid group or a sulfo group can be also used, and specificexamples thereof include dimethylol acetic acid, dimethylol propionicacid, and dimethylol butyric acid.

Preferred examples of polyurethane include polyether-based polyurethane,polyester-based polyurethane, and polycarbonate-based polyurethanerespectively obtained by using polyether-based diol, polyester-baseddiol, and polycarbonate-based diol as a diol compound.

Particularly, a urethane resin to which an acidic group is introducedusing a diol having an acidic group such as a carboxy group or a sulfogroup is desirable.

Polyurethane obtained by neutralizing an acidic group can be used.Examples of a base used for neutralization include alkylamine such asbutylamine or trimethylamine; alkanolamine such as monoethanolamine,diethanolamine, or triethanolamine; cyclic amine such as morpholine;ammonia; and an inorganic salt such as sodium hydroxide.

[Polyurea]

The polyurea includes polymers having a urea bond (—NRC(═O)NR— (here, Rrepresents a hydrogen atom or a substituent)) in the main chain or thegraft chain and derivatives thereof. It is preferable that the mainchain has a urea bond.

The polyurea is basically synthesized through a polyaddition reactionbetween a diamine compound and a diisocyanate compound or adeammoniation reaction between a diamine compound and urea.

Examples of the diamine compound include ethylenediamine,1,3-propanediamine, 1,2-propanediamine, hexamethylenediamine,octamethylenediamine, o-phenylenediamine, m-phenylenediamine,p-phenylenediamine, piperazine, 2,5-dimethylpiperazine,4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, andxylylenediamine.

Examples of the diisocyanate compound include the diisocyanate compoundsexemplified in the section of the polyurethane above.

[Polyester]

The polyester includes polymers having an ester bond (—C(═O)O—) in themain chain or the graft chain and derivatives thereof. It is preferablethat the main chain has an ester bond.

The polyester is basically synthesized through dehydration condensationbetween a diol compound and a dicarboxylic acid compound.

Examples of the dicarboxylic acid compound include oxalic acid, malonicacid, succinic acid, glutaric acid, dimethyl malonic acid, adipic acid,pimelic acid, α,α-dimethylsuccinic acid, acetonedicarboxylic acid,sebacic acid, 1,9-nonanedicarboxylic acid, fumaric acid, maleic acid,itaconic acid, citraconic acid, phthalic acid, isophthalic acid,terephthalic acid, 2-butylterephthalic acid, tetrachloroterephthalicacid, acetylenedicarboylic acid, poly(ethyleneterephthalate)dicarboxylicacid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboylic acid,ω-poly(ethyleneoxide)dicarboxylic acid, and p-xylylenedicarboxylic acid.

When a polycondensation reaction is performed between a dicarboxylicacid compound and a diol compound, the dicarboxylic acid compound can beused in the form of an alkyl ester (such as dimethyl ester) ofdicarboxylic acid or an acid chloride of dicarboxylic acid or in theform of an acid anhydride such as maleic anhydride, succinic anhydride,or phthalic anhydride.

A dicarboxylic acid compound having an ionic group, for example, ananionic group such as a sulfo group, a sulfuric monoester group,—OPO(OH)₂, a sulfinic acid group, or salts of these (for example, alkalimetal salts such as Na and K or ammonium salts such as ammonia,dimethylamine, ethanolamine, diethanolamine, triethanolamine, andtrimethylamine) in addition to a carboxy group or a cationic group suchas a primary amine, a secondary amine, a tertiary amine, or a quaternaryammonium salt can be used as the dicarboxylic acid compound. As theionic group, an anionic group is preferable and a sulfo group isparticularly preferable.

Preferred examples of the dicarboxylic acid having a sulfo group includesulfophthalic acid (such as 3-sulfophthalic acid, 4-sulfophthalic acid,4-sulfoisophthalic acid, 5-sulfoisophthalic acid, or 2-sulfoterephthalicacid), sulfosuccinic acid, sulfonaphthalenedicarboxylic acid (such as4-sulfo-1,8-naphthalenedicarboxylic acid or7-sulfo-1,5-naphthalenedicarboxylic acid),3,5-di(2-hydroxy)ethyloxycarbonylbenzenesulfonic acid, and salts ofthese.

Examples of the diol compound include the diol compounds exemplified inthe section of polyurethane above.

Water-soluble polyester can be preferably used as the polyester.Examples of commercially available products include NICHIGO POLYESTERseries (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)and Plus Coat series (manufactured by GOO CHEMICAL CO., LTD.).

[Polycarbonate]

The polycarbonate includes polymers having a carbonate bond (—OCOO—) inthe main chain or the graft chain and derivatives thereof. It ispreferable that the main chain has a carbonate bond.

The polycarbonate is basically synthesized through a reaction between adiol compound and phosgene or a carbonic acid ester derivative (forexample, aromatic ester such as diphenyl carbonate).

Examples of the diol compound include the diol compounds exemplified inthe section of polyurethane.

The raw materials such as a diamine compound and a dicarboxylic acidcompound used for synthesis of the specific polymers may be used aloneor two or more kinds thereof may be mixed at an arbitrary ratio and thenused depending on the various purposes thereof (for example, adjustmentof the glass transition temperature (Tg) of a specific polymer,solubility, coating properties of a treatment solution, or stability).

It is preferable that the specific polymer of the present inventionincludes at least one group (hereinafter, also referred to as a specificfunctional group) selected from a carboxy group, a sulfo group, aphosphoric acid group, a phosphonic acid group, a sulfuric acid group,an amino group, and a polyalkylene oxide group.

Among the examples of the specific functional groups, some or all of theacidic groups (a carboxy group, a sulfo group, a phosphoric acid group,a phosphonic acid group, and a sulfuric acid group) and alkali metals(Li, Na, K, and the like) or alkaline earth metals (Mg, Ca, and thelike) may form salts.

An amino group may form an ammonium group. The ammonium group includes agroup formed by drawing out one hydrogen atom from primary to quaternaryammoniums in which H in NH₄ ⁺ is substituted with an alkyl group, anaryl group, or an aralkyl group. Among these, a group formed by drawingone hydrogen atom from the quaternary ammonium is preferable. Theammonium group may be chain-like or cyclic.

As the alkyl group, a linear, branched, or cyclic alkyl group having 1to 12 carbon atoms is preferable. Specific examples of the alkyl groupinclude, a methyl group, an ethyl group, a propyl group, a butyl group,a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, an isopropyl group, an isobutyl group, a sec-butyl group, atert-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutylgroup, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, acyclohexyl group, a cyclopentyl group, and a 2-norbornyl group.

As the aryl group, an aryl group having 6 to 20 carbon atoms ispreferable. Specific examples of the aryl group include a phenyl group,a biphenyl group, a naphthyl group, a tolyl group, a xylyl group, amesityl group, a cumenyl group, a chlorophenyl group, a bromophenylgroup, a chloromethylphenyl group, a hydroxyphenyl group, amethoxyphenyl group, an ethoxyphenyl group, a phenoxyphenyl group, anacetoxyphenyl group, a benzoyloxyphenyl group, a methylthiophenyl group,a phenylthiophenyl group, a methylaminophenyl group, adimethylaminophenyl group, an acetylaminophenyl group, a carboxyphenylgroup, a methoxycarbonylphenyl group, an ethoxycarbonylphenyl group, aphenoxycarbonylphenyl group, a N-phenylcarbamoylphenyl group, acyanophenyl group, a sulfophenyl group, a sulfonatophenyl group, aphosphonophenyl group, and a phosphonatophenyl group.

As the aralkyl group, an aralkyl group having 7 to 12 carbon atoms ispreferable. Specific examples of the aralkyl group include a benzylgroup, a phenethyl group, and a naphthylmethyl group.

As the polyalkylene oxide group, a polyalkylene oxide group having 2 to120 alkylene oxide units, each of which has 2 or 3 carbon atoms, ispreferable. A polyethylene oxide group having 2 to 120 ethylene oxideunits is more preferable and a polyethylene oxide group having 10 to 100ethylene oxide units is particularly preferable.

Among the specific functional groups, a carboxy group, a sulfo group, aphosphoric acid group, and a phosphonic acid group are preferable and asulfo group, a phosphoric acid group, and a phosphonic acid group aremore preferable.

A specific functional group can be introduced to each of theabove-described polymers using various methods. For example, a specificfunctional group may be introduced by producing each polymer using a rawmaterial compound having the specific functional group or the specificfunctional group may be introduced by carrying out a polymer reactionafter the polymer is produced. For example, in a case where the specificpolymer is polyurethane, a specific functional group can be introducedas a substituent in the main chain of the polymer using a diolcontaining an acidic group which is the specific functional group at thetime when the polyurethane is produced. Further, in a case where thespecific polymer is polyester, a carboxy group can be introduced bybeing allowed to remain as an unreacted terminal of dicarboxylic acid inthe terminal of polyester. In addition, an acidic group can beintroduced by reacting an acid anhydride (for example, maleic anhydride)with a reactive group such as a —OH group or an amino group present inthe terminal after each polymer is produced.

When the specific polymers of the present invention have theabove-described specific functional groups, there is an advantage thatthe solubility in a solvent used at the time of application is improved.Therefore, the specific polymers having the above-described specificfunctional groups can be desirably dissolved in a solvent used for acoating solution, such as water, a water-miscible organic solvent, or amixture of these.

Examples of the water-miscible organic solvent include alcohols (such asmethanol, ethanol, propanol, isopropanol, benzyl alcohol, ethyleneglycol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethyleneglycol monoethyl ether, diethylene glycol monohexyl ether, triethyleneglycol monomethyl ether, propylene glycol monoethyl ether, dipropyleneglycol monomethyl ether, polyethylene glycol monomethyl ether,polypropylene glycol, and tetraethylene glycol); ketones (such asacetone and methyl ethyl ketone); esters (such as methyl lactate, butyllactate, propylene glycol monomethyl ether acetate, and diethyleneglycol acetate); amides (such as dimethylformamide); and sulfoxide (suchas dimethyl sulfoxide).

Further, the specific polymers having the above-described specificfunctional groups are preferable from the viewpoints of exhibitingexcellent solubility in water or a solution including water as a maincomponent, which is used at the time of development of the lithographicprinting plate precursor, such as an alkaline aqueous solution, anacidic aqueous solution, an aqueous solution containing a surfactant, oran aqueous solution containing an organic solvent.

Therefore, the specific polymers having the specific functional groupsare also advantageous in that the specific polymers further contributepromotion of on-press development and suppression of edge stain due tohydrophilization of a support.

From the above-described viewpoint, the solubility of the specificpolymer of the present invention in water at 20° C. is preferably 10 g/Lor greater, more preferably 30 g/L or greater, and still more preferably50 g/L or greater.

The main chain of the specific polymer according to the presentinvention may contain two or more kinds of bonds included in the mainchain of the specific polymer, that are, an amide bond, a urethane bond,a urea bond, an ester bond, and a carbonate bond. Examples thereofinclude polyurethane polyurea having a urethane bond and a urea bond andpolycarbonate-based polyurethane having a carbonate bond and a urethanebond. In a case where the specific polymer of the present invention is apolymer having two or more kinds of bonds, this specific polymer isclassified into a polymer of the bond with the highest content. Forexample, in a polymer having a urethane bond and a urea bond, thepolymer is classified into polyurethane in a case where the content ofthe urethane bond is greater than the content of the urea bond.

The weight average molecular weight (Mw) of the specific polymeraccording to the present invention is preferably in a range of 2000 to1000000, more preferably in a range of 5000 to 500000, and still morepreferably in a range of 10000 to 200000. In the present specification,unless otherwise specified, the weight average molecular weight of thespecific polymers and other polymer compounds is a value in terms ofstandard polystyrene obtained by performing measurement using gelpermeation chromatography (GPC). The measurement using gel permeationchromatography (GPC) is performed under the following conditions.

Concentration of sample: 0.2% by mass

Column: TSKgel α-M+TSKgel α-2500 (manufactured by Tosho Corporation)

Eluant: 100 mM NaNO₃ aqueous solution

Flow rate: 0.35 ml/min

Detector: differential refractive index (RI) detector

Temperature: 40° C.

The form of the specific polymer according to the present invention isnot particularly limited. Examples thereof typically include an emulsiontype such as a self-emulsifying emulsion or a self-stabilizing type inaddition to a solid type (such as powdery, granular, or paste-like).

Any position from the top of a support and the top of a top layerconstituting the lithographic printing plate precursor may contain thespecific polymer according to the present invention. For example, in acase where the lithographic printing plate precursor has an undercoatlayer, an image recording layer, and a protective layer in this order onthe support, the specific polymer may be present in any position ofbetween the support and the undercoat layer, in the undercoat layer,between the undercoat layer and the image recording layer, in the imagerecording layer, between the image recording layer and the protectivelayer, in the protective layer, and on the protective layer. Further,the specific polymer may be present in plural positions. In the case ofthe lithographic printing plate precursor having the above-describedconfiguration, the specific polymer may be present between the supportand the undercoat layer and in the undercoat layer, between the supportand the undercoat layer and in the undercoat layer and between theundercoat layer and the image recording layer, and in the protectivelayer and on the protective layer. In order to prevent the imagerecording layer from remaining on the support which is assumed to causeedge stain, it is preferable that the specific polymer of the presentinvention is present between the support and the image recording layer.Specifically, it is preferable that the specific polymer is presentbetween the support and the undercoat layer, in the undercoat layer,between the undercoat layer and the image recording layer, between thesupport and the undercoat layer and in the undercoat layer, between thesupport and the undercoat layer and in the undercoat layer, and betweenthe undercoat layer and the image recording layer. The specific polymermay be allowed to be present in a specific position of the lithographicprinting plate precursor by applying a coating solution containing thespecific polymer to the specific position of the lithographic printingplate precursor. A specific method thereof will be described below asthe method of producing a lithographic printing plate precursor.

It is preferable that the region on the plate surface on the imagerecording layer side from the end portion according to the presentinvention to a portion inside the end portion by 5 mm further contains ahydrophilic compound in addition to the specific polymer. A hydrophiliccompound has an effect of preventing stain from being generated due toprinting ink being accumulated in cracks which may be generated at thetime when a shear drop shape described below is formed, by means ofhydrophilizing the cracks.

A water-soluble compound is preferable as the hydrophilic compound. Forexample, as the hydrophilic compound, a compound dissolved in 100 g ofwater at 20° C. by an amount of 0.5 g or greater is preferable and acompound dissolved in 100 g of water at 20° C. by an amount of 2 g orgreater is more preferable.

It is preferable that the hydrophilic compound includes ahydrophilizable compound in addition to the specific polymer. Thesupport-adsorptive group is an adsorptive group which can be adsorbed tothe surface of the support of the lithographic printing plate precursor.Preferred examples thereof include a phenolic hydroxy group, a carboxygroup, a —PO₃H₂ group, a —OPO₃H₂ group, a —CONHSO₂— group, a —SO₂NHSO₂—group, and a —COCH₂COCH₃ group. Among these, a —PO₃H₂ group and a—OPO₃H₂ group are preferable. Hereinafter, a phosphoric acid compoundand a phosphonic acid compound which include a —PO₃H₂ group and a—OPO₃H₂ group will be described in detail.

(Phosphoric Acid Compound)

A phosphoric acid compound includes phosphoric acid, a salt thereof, andan ester thereof. Examples of the phosphoric acid compound includephosphoric acid, metaphosphoric acid, monoammonium phosphate, ammoniumsecondary phosphate, sodium dihydrogen phosphate, sodium monohydrogenphosphate, potassium primary phosphate, potassium secondary phosphate,sodium tripolyphosphate, potassium pyrophosphate, and sodiumhexametaphosphate. Among these, sodium dihydrogen phosphate, sodiummonohydrogen phosphate, or sodium hexametaphosphate are preferably used.

As the phosphoric acid compound, a polymer compound is preferable and apolymer compound having a phosphoric acid monoester group is morepreferable. A specific polymer-containing coating solution havingexcellent coating properties is obtained.

Examples of the polymer compound having a phosphoric acid ester groupinclude a polymer formed of one or more kinds of monomers having aphosphoric acid ester group in a molecule, a copolymer of one or morekinds of monomers having a phosphoric acid ester group and one or morekinds of monomers that do not have a phosphoric acid ester group, and apolymer obtained by introducing a phosphoric acid ester group into apolymer that does not have a phosphoric acid ester group through apolymer reaction.

Examples of the monomer having a phosphoric acid ester group includemono(2-methacryloyloxyethyl) acid phosphate,mono(2-methacryloyloxypolyoxyethyleneglycol) acid phosphate,mono(2-acryloyloxyethyl) acid phosphate, 3-chloro-2-acidphosphooxypropyl methacrylate, acid phosphooxy polyoxyethylene glycolmonomethacrylate, acid phosphooxy polyoxypropylene glycol methacrylate,(meth)acryloyloxy ethyl acid phosphate, (meth)acryloyloxy propyl acidphosphate, (meth)acryloyloxy-2-hydroxy propyl acid phosphate,(meth)acryloyloxy-3-hydroxy propyl acid phosphate,(meth)acryloyloxy-3-chloro-2-hydroxy propyl acid phosphate, and allylalcohol acid phosphate. Among these examples of monomers, from theviewpoint of preventing edge stain, mono(2-acryloyloxyethyl) acidphosphate is preferably used. Typical examples of commercially availableproducts include LIGHT ESTER P-1M (manufactured by Kyoei Kagaku KogyoCo., Ltd.) and PHOSMER PE (manufactured by Uni-Chemical Co., Ltd.).

As a monomer which does not have a phosphoric acid ester group in thecopolymer, a monomer having a hydrophilic group is preferable. Examplesof the hydrophilic group include a hydroxy group, an alkylene oxidestructure, an amino group, an ammonium group, and an amide group. Amongthese, a hydroxy group, an alkylene oxide structure, or an amide groupis preferable, an alkylene oxide structure which has 1 to 20 alkyleneoxide units having 2 or 3 carbon atoms is more preferable, and apolyethylene oxide structure having 2 to 10 ethylene oxide units isstill more preferable. Examples thereof include 2-hydroxy ethylacrylate, ethoxy diethylene glycol acrylate, methoxy triethylene glycolacrylate, poly(oxyethylene) methacrylate, N-isopropylacrylamide, andacrylamide.

The proportion of the repeating unit having a phosphoric acid estergroup in the polymer compound having a phosphoric acid ester group ispreferably in a range of 1% to 100% by mole, more preferably in a rangeof 5% to 100% by mole, and still more preferably in a range of 10% to100% by mole.

The weight-average molecular weight of the polymer compound having aphosphoric acid ester group is preferably in a range of 5,000 to1,000,000, more preferably in a range of 7,000 to 700,000, andparticularly preferably in a range of 10,000 to 500,000.

(Phosphonic Acid Compound)

A phosphonic acid compound includes phosphonic acid, a salt thereof, andan ester thereof. Examples of the phosphonic acid compound include ethylphosphonic acid, propyl phosphonic acid, isopropyl phosphonic acid,butyl phosphonic acid, hexyl phosphonic acid, octyl phosphonic acid,dodecyl phosphonic acid, octadecyl phosphonic acid, 2-hydroxyethylphosphonic acid and sodium salts or potassium salts of these, alkylphosphonic acid monoalkyl ester such as methyl phosphonic acid methylester, ethyl phosphonic acid methyl ester, or 2-hydroxyethyl phosphonicacid methyl ester and sodium salts or potassium salts of these, alkylenediphosphonic acid such as methylene diphosphonic acid or ethylenediphosphonic acid and sodium salts or potassium salts of these, andpolyvinyl phosphonic acid.

As the phosphonic acid compound, a polymer compound is preferable. Aspecific polymer-containing coating solution having excellent coatingproperties is obtained.

Preferred examples of the polymer compound as a phosphonic acid compoundinclude polyvinyl phosphonic acid, a polymer formed of one or moremonomers having a phosphonic acid group or a phosphonic acid monoestergroup in a molecule, and a copolymer of one or more kinds of monomershaving a phosphonic acid group or a phosphonic acid monoester group andone or more kinds of monomers which do not have a phosphonic acid groupand a phosphonic acid monoester group.

Examples of the monomer having a phosphonic acid group includevinylphosphonic acid, ethyl phosphonic acid monovinyl ester, acryloylaminomethyl phosphonic acid, and 3-methacryloyloxy propyl phosphonicacid.

As the polymer compound, both of a homopolymer and a copolymer ofmonomers having a phosphonic acid ester group are also used. As thecopolymer, for example, a copolymer of a monomer having a phosphonicacid ester group and a monomer having a hydrophilic group or a copolymerof a monomer having a phosphonic acid ester group and a monomer whichdoes not have both of a phosphonic acid ester group and a hydrophilicgroup can be used.

In the monomers having a hydrophilic group in the copolymers, examplesof the hydrophilic group include a hydroxy group, an alkylene oxidestructure, an amino group, an ammonium group, and an amide group. Amongthese, a hydroxy group, an alkylene oxide structure, or an amide groupis preferable, an alkylene oxide structure which has 1 to 20 alkyleneoxide units having 2 or 3 carbon atoms is more preferable, and apolyethylene oxide structure having 2 to 10 ethylene oxide units isstill more preferable. Examples thereof include 2-hydroxy ethylacrylate, ethoxy diethylene glycol acrylate, methoxy triethylene glycolacrylate, poly(oxyethylene) methacrylate, N-isopropylacrylamide, andacrylamide.

The proportion of the repeating unit having a phosphonic acid estergroup in the polymer compound having a phosphonic acid ester group ispreferably in a range of 1% to 100% by mole, more preferably in a rangeof 3% to 100% by mole, and still more preferably in a range of 5% to100% by mole.

The weight-average molecular weight of the polymer compound having aphosphonic acid ester group is preferably in a range of 5,000 to1,000,000, more preferably in a range of 7,000 to 700,000, andparticularly preferably in a range of 10,000 to 500,000.

From the viewpoint of workability, it is preferable that theabove-described hydrophilic compound is allowed to be contained in theregion on the plate surface on the image recording layer side from theend portion of the lithographic printing plate precursor to a portioninside the end portion by 5 mm at the same time when the specificpolymer is applied to the lithographic printing plate precursor.Specifically, both of the steps can be easily performed by adding ahydrophilic compound to a coating solution that contains the specificpolymer and coating the lithographic printing plate precursor with thecoating solution.

[Lithographic Printing Plate Precursor]

The lithographic printing plate precursor of the present invention hasan image recording layer on the support. The lithographic printing plateprecursor may have an undercoat layer between the support and the imagerecording layer and a protective layer on the image recording layer asnecessary.

[Image Recording Layer]

The image recording layer of the lithographic printing plate precursoris an image recording layer in which the non-image portion is removed byat least one of acidic to alkaline dampening water or printing ink on aprinting press.

According to one aspect of the present invention, the image recordinglayer is an image recording layer (hereinafter, also referred to as animage recording layer A) that contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer.

According to another aspect of the present invention, the imagerecording layer is an image recording layer (hereinafter, also referredto as an image recording layer B) that contains an infrared absorbingagent, a polymerization initiator, a polymerizable compound, and aparticulate polymer compound.

According to still another aspect of the present invention, the imagerecording layer is an image recording layer (hereinafter, also referredto as an image recording layer C) that contains an infrared absorbingagent and thermoplastic polymer fine particles.

(Image Recording Layer A)

The image recording layer A contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer. Hereinafter, the constituent components of the image recordinglayer A will be described.

<Infrared Absorbing Agent>

An infrared absorbing agent has a function of converting absorbedinfrared rays into heat, a function of electron transfer to apolymerization initiator described below through excitation by infraredrays, and/or a function of energy transfer. As the infrared absorbingagent used in the present invention, a dye or a pigment having maximumabsorption at a wavelength of 760 to 1,200 nm is preferable and a dyehaving maximum absorption at a wavelength of 760 to 1,200 nm is morepreferable.

As the dye, dyes described in paragraphs [0082] to [0088] ofJP2014-104631A can be used and the contents of which are incorporated inthe specification of the present application.

The particle diameter of the pigment is preferably in a range of 0.01 to1 μm and more preferably in a range of 0.01 to 0.5 μm. A knowndispersion technique used to produce inks or toners can be used fordispersion of the pigment. The details are described in “Latest PigmentApplication Technology” (CMC Publishing Co., Ltd., 1986) and the like.

The infrared absorbing agent may be used alone or in combination of twoor more kinds thereof.

The content of the infrared absorbing agent is preferably in a range of0.05 to 30 parts by mass, more preferably in a range of 0.1 to 20, andparticularly preferably in a range of 0.2 to 10 parts by mass withrespect to 100 parts by mass of the total solid content of the imagerecording layer.

<Polymerization Initiator>

The polymerization initiator indicates a compound that initiates andpromotes polymerization of a polymerizable compound. As thepolymerization initiator, a known thermal polymerization initiator, acompound having a bond with small bond dissociation energy, or aphotopolymerization initiator can be used. Specifically, radicalpolymerization initiators described in paragraphs [0092] to [0106] ofJP2014-104631A can be used and the contents of which are incorporated inthe specification of the present application.

Preferred examples of compounds in the polymerization initiators includeonium salts such as iodonium salts and sulfonium salts. Specificpreferred examples of the compounds in each of the salts are thecompounds described in paragraphs [0104] to [0106] of JP2014-104631A andthe contents of which are incorporated in the specification of thepresent application.

The content of the polymerization initiator is preferably in a range of0.1% to 50% by mass, more preferably in a range of 0.5% to 30% by mass,and particularly preferably in a range of 0.8% to 20% by mass withrespect to the total solid content of the image recording layer. Whenthe content thereof is in the above-described range, improvedsensitivity and improved stain resistance of a non-image portion at thetime of printing are obtained.

<Polymerizable Compound>

A polymerizable compound is an addition polymerizable compound having atleast one ethylenically unsaturated double bond and is selected fromcompounds having at least one and preferably two or more terminalethylenically unsaturated bonds. These have chemical forms such as amonomer, a pre-polymer, that is, a dimer, a trimer, an oligomer, and amixture of these. Specifically, polymerizable compounds described inparagraphs [0109] to [0113] of JP2014-104631A can be used and thecontents of which are incorporated in the specification of the presentapplication.

Among the examples described above, from the viewpoint that the balancebetween hydrophilicity associated with on-press developability andpolymerization ability associated with printing durability is excellent,isocyanuric acid ethylene oxide-modified acrylates such astris(acryloyloxyethyl) isocyanurate andbis(acryloyloxyethyl)hydroxyethyl isocyanurate are particularlypreferable.

The details of the structures of these polymerizable compounds, whetherto be used alone or in combination, and the usage method such as theaddition amount can be arbitrarily set according to the finalperformance design of a lithographic printing plate precursor. Thecontent of the above-described polymerizable compound to be used ispreferably in a range of 5% to 75% by mass, more preferably in a rangeof 10% to 70% by mass, and particularly preferably in a range of 15% to60% by mass with respect to the total solid content of the imagerecording layer.

<Binder Polymer>

A binder polymer can be mainly used to improve the film hardness of theimage recording layer. As the binder polymer, known polymers of therelated art can be used and polymers having coated-film properties arepreferable. Among examples thereof, an acrylic resin, a polyvinyl acetalresin, and a polyurethane resin are preferable.

Preferred examples of the binder polymers include polymers having across-linking functional group in the main or side chain, preferably inthe side chain, for improving coated-film strength of an image portionas described in JP2008-195018A. Cross-linking occurs between polymermolecules by a cross-linking group so that curing is promoted.

Preferred examples of the cross-linking functional group include anethylenically unsaturated group such as a (meth)acryl group, a vinylgroup, an allyl group, or a styryl group and an epoxy group, and thecross-linking functional groups can be introduced into a polymer by apolymer reaction or copolymerization. For example, a reaction between anacrylic polymer having a carboxy group in the side chain thereof orpolyurethane and glycidyl methacrylate or a reaction between a polymerhaving an epoxy group and ethylenically unsaturated group-containingcarboxylic acid such as methacrylic acid can be used.

The content of the cross-linking group in the binder polymer ispreferably in a range of 0.1 to 10.0 mmol, more preferably in a range of0.25 to 7.0 mmol, and particularly preferably in a range of 0.5 to 5.5mmol with respect to 1 g of the binder polymer.

Moreover, it is preferable that the binder polymer includes ahydrophilic group. The hydrophilic group contributes to providingon-press developability for the image recording layer. Particularly, inthe coexistence of a cross-linking group and a hydrophilic group, bothof printing durability and on-press developability can be achieved.

Examples of the hydrophilic group include a hydroxy group, a carboxygroup, an alkylene oxide structure, an amino group, an ammonium group,an amide group, a sulfo group, and a phosphoric acid group. Among these,an alkylene oxide structure having 1 to 9 alkylene oxide units having 2or 3 carbon atoms is preferable. A monomer having a hydrophilic groupmay be copolymerized in order to provide a hydrophilic group for abinder polymer.

In addition, in order to control the impressing property, a lipophilicgroup such as an alkyl group, an aryl group, an aralkyl group, or analkenyl group can be introduced into the binder polymer. For example, alipophilic group-containing monomer such as methacrylic acid alkyl estermay be copolymerized.

The weight-average molecular weight (Mw) of the binder polymer ispreferably 2,000 or greater, more preferably 5,000 or greater, and stillmore preferably in a range of 10,000 to 300,000.

The content of the binder polymer is practically in a range of 3% to 90%by mass, preferably in a range of 5% to 80% by mass, and more preferablyin a range of 10% to 70% by mass with respect to the total solid contentof the image recording layer.

As a preferred example of the binder polymer, a polymer compound havinga polyoxyalkylene chain in the side chain is exemplified. When the imagerecording layer contains a polymer compound having a polyoxyalkylenechain in the side chain (hereinafter, also referred to as a POAchain-containing polymer compound), permeability of dampening water ispromoted and on-press developability is improved.

Examples of the resin constituting the main chain of the POAchain-containing polymer compound include an acrylic resin, a polyvinylacetal resin, a polyurethane resin, a polyurea resin, a polyimide resin,a polyamide resin, an epoxy resin, a methacrylic resin, a polystyreneresin, a novolac type phenolic resin, a polyester resin, syntheticrubber, and natural rubber. Among these, an acrylic resin isparticularly preferable.

The POA chain-containing polymer compound does not substantially containa perfluoroalkyl group. The expression “does not substantially contain aperfluoroalkyl group” means that the mass ratio of a fluorine atompresent as a perfluoroalkyl group in a polymer compound is less than0.5% by mass, and it is preferable that the polymer compound does notcontain a fluorine atom. The mass ratio of the fluorine atom is measuredby an elemental analysis method.

In addition, the “perfluoroalkyl group” is a group in which all hydrogenatoms of the alkyl group are substituted with fluorine atoms.

As alkylene oxide (oxyalkylene) in a polyoxyalkylene chain, alkyleneoxide having 2 to 6 carbon atoms is preferable, ethylene oxide(oxyethylene) or propyleneoxide (oxypropylene) is more preferable, andethylene oxide is still more preferable.

The repetition number of the alkylene oxide in a polyoxyalkylene chain,that is, a poly(alkyleneoxide) moiety is preferably in a range of 2 to50 and more preferably in a range of 4 to 25.

When the repetition number of the alkylene oxide is 2 or greater, thepermeability of dampening water is sufficiently improved. Further, fromthe viewpoint that printing durability is not degraded due to abrasion,it is preferable that the repetition number thereof is 50 or less.

As the poly(alkyleneoxide) moiety, structures described in paragraphs[0060] to [0062] of JP2014-104631A are preferable and the contents ofwhich are incorporated in the specification of the present application.

The POA chain-containing polymer compound may have cross-linkingproperties in order to improve coated-film strength of an image portion.Examples of the POA chain-containing polymer compounds havingcross-linking properties are described in paragraphs [0063] to [0072] ofJP2014-104631A and the contents of which are incorporated in thespecification of the present application.

The proportion of repeating units having a poly(alkyleneoxide) moiety inthe total repeating units constituting the POA chain-containing polymercompound is not particularly limited, but is preferably in a range of0.5% to 80% by mole and more preferably in a range of 0.5% to 50% bymole. Examples of the POA chain-containing polymer compounds aredescribed in paragraphs [0075] and [0076] of JP2014-104631A and thecontents of which are incorporated in the specification of the presentapplication.

As the POA chain-containing polymer compound, hydrophilic macromolecularcompounds such as polyacrylic acid and polyvinyl alcohol described inJP2008-195018A can be used in combination as necessary. Further, alipophilic polymer compound and a hydrophilic macromolecular compoundcan be used in combination.

In addition to the presence of the POA chain-containing polymer compoundin the image recording layer as a binder that plays a role of connectingimage recording layer components with each other, the specific polymercompound may be present in the form of fine particles. In a case wherethe specific polymer compound is present in the form of fine particles,the average particle diameter is in a range of 10 to 1,000 nm,preferably in a range of 20 to 300 nm, and particularly preferably in arange of 30 to 120 nm.

The content of the POA chain-containing polymer compound is preferablyin a range of 3% to 90% by mass and more preferably in a range of 5% to80% by mass with respect to the total solid content of the imagerecording layer. When the content thereof is in the range of 3% to 90%by mass, both of permeability of dampening water and image formabilitycan be reliably achieved.

Other preferred examples of the binder polymer include a polymercompound (hereinafter, also referred to as a “star type polymercompound”) which has a polymer chain bonded to a nucleus through asulfide bond by means of using a polyfunctional, in a range of hexa- todeca-functional, thiol as the nucleus and in which the polymer chain hasa polymerizable group. As the star type polymer compound, for example,compounds described in JP2012-148555A can be preferably used.

Examples of the star type polymer compound include compounds having apolymerizable group such as an ethylenically unsaturated bond in themain chain or in the side chain, preferably in the side chain, forimproving coated-film strength of an image portion as described inJP2008-195018A. Cross-linking occurs between polymer molecules by apolymerizable group so that curing is promoted.

Preferred examples of the polymerizable group include an ethylenicallyunsaturated group such as a (meth)acryl group, a vinyl group, an allylgroup, or a styryl group and an epoxy group. Among these, from theviewpoint of polymerization reactivity, a (meth)acryl group, a vinylgroup, or a styryl group is more preferable and a (meth)acryl group isparticularly preferable. These groups can be introduced into a polymerby a polymer reaction or copolymerization. For example, a reactionbetween a polymer having a carboxy group in the side chain thereof andglycidyl methacrylate or a reaction between a polymer having an epoxygroup and ethylenically unsaturated group-containing carboxylic acidsuch as methacrylic acid can be used. These groups may be used incombination.

The content of the cross-linking group in the star type polymer compoundis preferably in a range of 0.1 to 10.0 mmol, more preferably in a rangeof 0.25 to 7.0 mmol, and most preferably in a range of 0.5 to 5.5 mmolwith respect to 1 g of the star type polymer compound.

Moreover, it is preferable that the star type polymer compound furtherincludes a hydrophilic group. The hydrophilic group contributes toproviding on-press developability for the image recording layer.Particularly, in the coexistence of a polymerizable group and ahydrophilic group, both of printing durability and developability can beachieved.

Examples of the hydrophilic group include —SO₃M¹, —OH, —CONR¹R² (M¹represents hydrogen, a metal ion, an ammonium ion, or a phosphonium ion,R¹ and R² each independently represent a hydrogen atom, an alkyl group,an alkenyl group, or an aryl group, and R¹ and R² may be bonded to eachother to form a ring), —N⁺R³R⁴R⁵X⁻ (R³ to R⁵ each independentlyrepresent an alkyl group having 1 to 8 carbon atoms and X⁻ represents acounter anion), a group represented by the following Formula (1), and agroup represented by the following Formula (2).

—(CH₂CH₂O)_(n)R  Formula (1)

—(C₃H₆O)_(m)R  Formula (2)

In the above-described formulae, n and m each independently represent aninteger of 1 to 100 and R's each independently represent a hydrogen atomor an alkyl group having 1 to 18 carbon atoms.

Here, in a case where the star type polymer compound is a star typepolymer compound having a polyoxyalkylene chain (for example, a grouprepresented by the above-described Formula (1) or (2)) in the sidechain, such a star type polymer compound is a polymer compound havingthe above-described polyoxyalkylene chain in the side chain.

Among these hydrophilic groups, —CONR¹R², groups represented by Formula(1), and groups represented by Formula (2) are preferable, —CONR¹R² andgroups represented by Formula (1) are more preferable, and groupsrepresented by Formula (1) are particularly preferable. Among the groupsrepresented by Formula (1), n represents an integer of preferably 1 to10 and particularly preferably 1 to 4. Further, R represents morepreferably a hydrogen atom or an alkyl group having 1 to 4 carbon atomsand particularly preferably a hydrogen atom or a methyl group. Thesehydrophilic groups may be used in combination of two or more kindsthereof.

Further, it is preferable that the star type polymer compound does notsubstantially include a carboxylic acid group, a phosphoric acid group,or a phosphonic acid group. Specifically, the amount of these acidgroups is preferably less than 0.1 mmol/g, more preferably less than0.05 mmol/g, and particularly preferably 0.03 mmol/g or less. When theamount of these acid groups is less than 0.1 mmol/g, developability isfurther improved.

In order to control impressing properties, a lipophilic group such as analkyl group, an aryl group, an aralkyl group, or an alkenyl group can beintroduced to the star type polymer compound. Specifically, a lipophilicgroup-containing monomer such as methacrylic acid alkyl ester may becopolymerized.

Specific examples of the star type polymer compound include compoundsdescribed in paragraphs [0153] to [0157] of JP2014-104631A and thecontents of which are incorporated in the specification of the presentapplication.

The star type polymer compound can be synthesized, using a known method,by performing radical polymerization on the above-described monomersconstituting a polymer chain in the presence of the above-describedpolyfunctional thiol compound.

The weight-average molecular weight (Mw) of the star type polymercompound is preferably in a range of 5,000 to 500,000, more preferablyin a range of 10,000 to 250,000, and particularly preferably in a rangeof 20,000 to 150,000. When the weight-average molecular weight thereofis in the above-described range, the on-press developability and theprinting durability are more improved.

The star type polymer compound may be used alone or in combination oftwo or more kinds thereof. Further, the star type polymer compound maybe used in combination with a typical linear binder polymer.

The content of the star type polymer compound is preferably in a rangeof 5% to 95% by mass, more preferably in a range of 10% to 90% by mass,and particularly preferably in a range of 15% to 85% by mass withrespect to the total solid content of the image recording layer.

From the viewpoint of promoting the permeability of dampening water andimproving the on-press developability, star type polymer compoundsdescribed in JP2012-148555A are particularly preferable.

<Other Components>

The image recording layer A can contain other components describedbelow.

(1) Low-Molecular Weight Hydrophilic Compound

In order to improve the on-press developability without degrading theprinting durability, the image recording layer may contain alow-molecular weight hydrophilic compound.

As the low-molecular weight hydrophilic compound, examples of awater-soluble organic compound include glycols such as ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol, dipropyleneglycol, and tripropylene glycol and ether or ester derivatives thereof;polyols such as glycerin, pentaerythritol, and tris(2-hydroxyethyl)isocyanurate; organic amines such as triethanolamine, diethanolamine,and monoethanolamine and salts thereof; organic sulfonic acids such asalkylsulfonic acid, toluenesulfonic acid, and benzenesulfonic acid andsalts thereof; organic sulfamic acids such as alkyl sulfamic acid andsalts thereof; organic sulfuric acids such as alkyl sulfuric acid andalkyl ether sulfuric acid and salts thereof; organic phosphonic acidssuch as phenyl phosphonic acid and salts thereof; organic carboxylicacids such as tartaric acid, oxalic acid, citric acid, malic acid,lactic acid, gluconic acid, and amino acids and salts thereof; andbetaines.

Among these, it is preferable that the image recording layer contains atleast one selected from the group consisting of polyols, organicsulfates, organic sulfonates, and betaines.

Specific examples of the compounds of the organic sulfonates includecompounds described in paragraphs [0026] to [0031] of JP2007-276454A andparagraphs [0020] to [0047] of JP2009-154525A. The salt may be potassiumsalt or lithium salt.

Examples of the organic sulfate include compounds described inparagraphs [0034] to [0038] of JP2007-276454A.

As betaines, compounds having 1 to 5 carbon atoms of hydrocarbonsubstituents to nitrogen atoms are preferable. Specific examples thereofinclude trimethyl ammonium acetate, dimethyl propyl ammonium acetate,3-hydroxy-4-trimethyl ammonio butyrate, 4-(1-pyridinio)butyrate,1-hydroxyethyl-1-imidazolioacetate, trimethyl ammonium methanesulfonate, dimethyl propyl ammonium methane sulfonate,3-trimethylammonio-1-propane sulfonate, and 3-(1-pyridinio)-1-propanesulfonate.

Since the low-molecular weight hydrophilic compound has a smallstructure of a hydrophobic portion and almost does not have a surfaceactive action, hydrophobicity or coated-film strength of an imageportion is not degraded by dampening water permeating into an imagerecording layer exposed portion (image portion) and ink receptivity orprinting durability of the image recording layer can be maintainedsatisfactorily.

The amount of the low-molecular weight hydrophilic compounds to be addedto the image recording layer is preferably in a range of 0.5% to 20% bymass with respect to the total amount of the solid content in the imagerecording layer. The amount thereof is more preferably in a range of 1%to 15% by mass and still more preferably in a range of 2% to 10% bymass. When the amount thereof is in the above-described range, excellenton-press developability and printing durability can be obtained.

These compounds may be used alone or in combination of two or more kindsthereof.

(2) Oil Sensitizing Agent

In order to improve the impressing property, an oil sensitizing agentsuch as a phosphonium compound, a nitrogen-containing low-molecularweight compound, or an ammonium group-containing polymer can be used forthe image recording layer. Particularly, in a case where a protectivelayer contains an inorganic layered compound, the above-describedcompounds function as a surface coating agent of the inorganic layeredcompound and prevent a degradation in impressing property due to theinorganic layered compound during the printing.

The phosphonium compound, the nitrogen-containing low-molecular weightcompound, and the ammonium group-containing polymer are described inparagraphs [0184] to [0190] of JP2014-104631A in detail and the contentsof which are incorporated in the specification of the presentapplication.

The content of the oil sensitizing agent is preferably in a range of0.01% to 30.0% by mass, more preferably in a range of 0.1% to 15.0% bymass, and still more preferably in a range of 1% to 10% by mass withrespect to the total solid content of the image recording layer.

(3) Other Components

The image recording layer may further contain other components such as asurfactant, a coloring agent, a printing-out agent, a polymerizationinhibitor, a higher fatty acid derivative, a plasticizer, inorganic fineparticles, an inorganic layered compound, a co-sensitizer, and a chaintransfer agent. Specifically, the compounds and the addition amountsdescribed in paragraphs [0114] to [0159] of JP2008-284817A, paragraphs[0023] to [0027] of JP2006-091479A, and paragraph [0060] ofUS2008/0311520A can be preferably used.

<Formation of Image Recording Layer A>

The image recording layer A is formed by dispersing or dissolving eachof the above-described required components in a known solvent to preparea coating solution, coating a support with the coating solution directlyor through an undercoat layer using a known method such as a bar coatercoating method, and drying the resultant, as described in paragraphs[0142] and [0143] of JP2008-195018A. The coating amount of the imagerecording layer (solid content) on the support to be obtained after thecoating and the drying varies depending on the applications thereof, butis preferably in a range of 0.3 to 3.0 g/m². When the coating amountthereof is in the above-described range, excellent sensitivity andexcellent film-coating characteristics of the image recording layer areobtained.

(Image Recording Layer B)

The image recording layer B contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a particulatepolymer compound. Hereinafter, the constituent components of the imagerecording layer B will be described.

Similarly, the infrared absorbing agent, the polymerization initiator,and the polymerizable compound described in the image recording layer Acan be used as an infrared absorbing agent, a polymerization initiator,and a polymerizable compound in the image recording layer B.

<Polymer Compound Having Particulate Shape>

It is preferable that the particulate polymer compound is selected fromthermoplastic polymer fine particles, thermally reactive polymer fineparticles, polymer fine particles having a polymerizable group, amicrocapsule encapsulating a hydrophobic compound, and a microgel(cross-linked polymer fine particle). Among these, polymer fineparticles having a polymerizable group and a microgel are preferable.According to a particularly preferred embodiment, the particulatepolymer compound includes at least one ethylenically unsaturatedpolymerizable group. Because of the presence of the particulate polymercompound, effects of improving the printing durability of an exposedportion and the on-press developability of an unexposed portion areobtained.

Preferred examples of the thermoplastic polymer fine particles includehydrophobic thermoplastic polymer fine particles described in ResearchDisclosure No. 33303 on January, 1992, JP1997-123387A (JP-H09-123387A),JP1997-131850A (JP-H09-131850A), JP1997-171249A (JP-H09-171249A),JP1997-171250A (JP-H09-171250A), and EP931647B.

Specific examples of a polymer constituting thermoplastic polymer fineparticles include homopolymers or copolymers of monomers such asacrylate or methacrylate having structures of ethylene, styrene, vinylchloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethylmethacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, andpolyalkylene, and mixtures of these. Among these, polystyrene, styrene,a copolymer containing acrylonitrile, and polymethylmethacrylate aremore preferable. The average particle diameter of the thermoplasticpolymer fine particles is preferably in a range of 0.01 to 3.0 μm.

Examples of the thermally reactive polymer fine particles includepolymer fine particles having a thermally reactive group. The thermallyreactive polymer fine particles are cross-linked by a thermal reactionand have hydrophobic regions formed by a change in functional groupsduring the cross-linking.

As the thermally reactive group in polymer fine particles having athermally reactive group, a functional group that performs any reactionmay be used as long as a chemical bond is formed, but a polymerizablegroup is preferable. Preferred examples of the polymerizable groupinclude an ethylenically unsaturated group that performs a radicalpolymerization reaction (such as an acryloyl group, a methacryloylgroup, a vinyl group, or an allyl group); a cationic polymerizable group(such as a vinyl group, a vinyloxy group, an epoxy group, or an oxetanylgroup); an isocyanate group that performs an addition reaction or ablock body thereof, an epoxy group, a vinyloxy group, and a functionalgroup having active hydrogen atoms as the reaction partners of these(such as an amino group, a hydroxy group, or a carboxy group); a carboxygroup that performs a condensation reaction and a hydroxy group or anamino group as a reaction partner thereof; and an acid anhydride thatperforms a ring opening addition reaction and an amino group or ahydroxy group as a reaction partner thereof.

The microcapsule is a microcapsule in which at least a part ofconstituent components of the image recording layer are encapsulated asdescribed in JP2001-277740A and JP2001-277742A. Further, the constituentcomponents of the image recording layer may be contained in a portionother than the microcapsule. Moreover, a preferred embodiment of theimage recording layer containing the microcapsule is an embodiment inwhich hydrophobic constituent components are encapsulated by amicrocapsule and hydrophilic constituent components are contained by aportion other than the microcapsule.

The microgel (cross-linked polymer fine particles) may contain a part ofthe constituent components of the image recording layer in at least oneof the surface or the inside thereof. From the viewpoints of imageforming sensitivity and printing durability, a reactive microgel havinga radical polymerizable group on the surface thereof is particularlypreferable.

The constituent components of the image recording layer can be made intomicrocapsules or microgel particles using a known method.

The average particle diameter of the particulate polymer compound is,preferably in a range of 0.01 to 3.0 μm, more preferably in a range of0.03 to 2.0 μm, and still more preferably in a range of 0.10 to 1.0 μm.When the average particle diameter thereof is in the above-describedrange, excellent resolution and temporal stability are obtained.

The content of the particulate polymer compound is preferably in a rangeof 5% to 90% by mass with respect to the total solid content of theimage recording layer.

<Other Components>

The image recording layer B can contain other components described inthe above-described image recording layer A as necessary.

<Formation of Image Recording Layer B>

The image recording layer B can be formed in the same manner as theimage recording layer A described above.

(Image Recording Layer C)

The image recording layer C contains an infrared absorbing agent andthermoplastic polymer fine particles. Hereinafter, the constituentcomponents of the image recording layer C will be described.

<Infrared Absorbing Agent>

The infrared absorbing agent contained in the image recording layer C isa dye or a pigment having maximum absorption at a wavelength of 760 to1,200 nm. A dye is more preferable.

As the dye, commercially available dyes and known dyes described in theliteratures (for example, “Dye Handbook” edited by The Society ofSynthetic Organic Chemistry, Japan, published in 1970, “InfraredAbsorbind Dyes” of “Chemical Industry”, p. 45 to 51, published on May,1986, and “Development and Market Trend of Functional Dyes in 1990's”Section 2.3 of Chapter 2 (CMC Publishing Co., Ltd., 1990)) and thepatents can be used. Specific preferred examples thereof includeinfrared absorbing dyes such as an azo dye, a metal complex salt azodye, a pyrazolone azo dye, an anthraquinone dye, a phthalocyanine dye, acarbonium dye, a quinone imine dye, a polymethine dye, and a cyaninedye.

Among these, infrared absorbing dyes having a water-soluble group areparticularly preferable from the viewpoint of addition to the imagerecording layer.

Specific examples of the infrared absorbing dyes are described below,but the present invention is not limited thereto.

As the pigments, commercially available pigments and pigments describedin Color Index (C. I.) Handbook, “Latest Pigment Handbook” (edited byJapan Pigment Technology Association, 1977), “Latest Pigment ApplicationTechnology” (CMC Publishing Co., Ltd., 1986), and “Printing InkTechnology” (CMC. Publishing Co., Ltd., 1984) can be used.

The particle diameter of the pigment is preferably in a range of 0.01 to1 μm and more preferably in a range of 0.01 to 0.5 μm. A knowndispersion technique used to produce inks or toners can be used as amethod of dispersing the pigment. The details are described in “LatestPigment Application Technology” (CMC Publishing Co., Ltd., 1986).

The content of the infrared absorbing agent is preferably in a range of0.1% to 30% by mass, more preferably in a range of 0.25% to 25% by mass,and particularly preferably in a range of 0.5% to 20% by mass withrespect to the solid content of the image recording layer. When thecontent thereof is in the above-described range, excellent sensitivityis obtained without damaging the film hardness of the image recordinglayer.

<Thermoplastic Polymer Fine Particles>

The glass transition temperature (Tg) of the thermoplastic polymer fineparticles is preferably in a range of 60° C. to 250° C. Tg of thethermoplastic polymer fine particles is more preferably in a range of70° C. to 140° C. and still more preferably in a range of 80° C. to 120°C.

Preferred examples of the thermoplastic polymer fine particles having aTg of 60° C. or higher include thermoplastic polymer fine particlesdescribed in Research Disclosure No. 33303 on January, 1992,JP1997-123387A (JP-H09-123387A), JP1997-131850A (JP-H09-131850A),JP1997-171249A (JP-H09-171249A), JP1997-171250A (JP-H09-171250A), andEP931647B.

Specific examples thereof include homopolymers or copolymers formed ofmonomers such as ethylene, styrene, vinyl chloride, methyl acrylate,ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidenechloride, acrylonitrile, and vinyl carbazole, and mixtures of these.Among these, polystyrene and polymethylmethacrylate are preferable.

The average particle diameter of the thermoplastic polymer fineparticles is preferably in a range of 0.005 to 2.0 μm. When the averageparticle diameter is extremely large, the resolution may be degraded.Further, when the average particle diameter is extremely small, temporalstability may be degraded. This value is used as the average particlediameter in a case where two or more kinds of thermoplastic polymer fineparticles are mixed with each other. The average particle diameterthereof is more preferably in a range of 0.01 to 1.5 μm and particularlypreferably in a range of 0.05 μm to 1.0 μm. The polydispersity in a casewhere two or more kinds of thermoplastic polymer fine particles aremixed with each other is preferably 0.2 or greater. The average particlediameter and the polydispersity are calculated by laser lightscattering.

The thermoplastic polymer fine particles may be used in combination oftwo or more kinds thereof. Specifically, at least two kinds ofthermoplastic polymer fine particles with different particle sizes or atleast two kinds of thermoplastic polymer fine particles with differentglass transition temperatures may be exemplified. When two or more kindsof thermoplastic polymer fine particles are used in combination,coated-film curing properties of an image portion are further improvedand printing durability in a case where a lithographic printing plate isobtained is further improved.

For example, in a case where thermoplastic polymer fine particles havingthe same particle size are used, voids are present between thethermoplastic polymer fine particles to some extent, the curingproperties of the coated-film are not desirable in some cases even whenthe thermoplastic polymer fine particles are melted and solidified byimage exposure. Meanwhile, in a case where thermoplastic polymer fineparticles having different particle sizes are used, the void volumebetween the thermoplastic polymer fine particles can be decreased andthus the coated-film curing properties of the image portion after imageexposure can be improved.

Further, in a case where thermoplastic polymer fine particles having thesame Tg are used, the thermoplastic polymer fine particles are notsufficiently melted and solidified and, accordingly, the coated-filmcuring properties are not desirable in some cases when an increase intemperature of the image recording layer resulting from image exposureis insufficient. Meanwhile, in a case where thermoplastic polymer fineparticles having different glass transition temperatures are used, thecoated-film curing properties of the image portion can be improved whenan increase in temperature of the image recording layer resulting fromimage exposure is insufficient.

In a case where two or more kinds of thermoplastic polymer fineparticles having different glass transition temperatures are used incombination, the Tg of at least one thermoplastic polymer fine particleis preferably 60° C. or higher. At this time, a difference in Tg ispreferably 10° C. or higher and more preferably 20° C. or higher. Inaddition, the content of the thermoplastic polymer fine particles havinga Tg of 60° C. or higher is 70% by mass or greater with respect to thetotal amount of all thermoplastic polymer fine particles.

The thermoplastic polymer fine particles may include a cross-linkinggroup. When thermoplastic polymer fine particles having a cross-linkinggroup are used, the cross-linking group is thermally reacted due to heatgenerated by an image-exposed portion, cross-linking occurs betweenpolymers, coated-film strength of an image portion is improved, andprinting durability becomes more excellent. As the cross-linking group,a functional group, in which any reaction may occur, is not limited aslong as a chemical bond is formed, and examples thereof include anethylenically unsaturated group that performs a polymerization reaction(such as an acryloyl group, a methacryloyl group, a vinyl group, or anallyl group); an isocyanate group that performs an addition reaction ora block body thereof, and a group having active hydrogen atoms as thereaction partners of these (such as an amino group, a hydroxy group, ora carboxy group); an epoxy group that performs an addition reaction andan amino group, a carboxy group or a hydroxy group as reaction partnersthereof; a carboxy group that performs a condensation reaction and ahydroxy group or an amino group; and an acid anhydride that performs aring opening addition reaction and an amino group or a hydroxy group.

Specific examples of the thermoplastic polymer fine particles having across-linking group include thermoplastic polymer fine particles havingcross-linking groups such as an acryloyl group, a methacryloyl group, avinyl group, an allyl group, an epoxy group, an amino group, a hydroxygroup, a carboxy group, an isocyanate group, an acid anhydride, and agroup protecting these. These cross-linking groups may be introduced topolymers at the time of polymerization of fine particle polymers or maybe introduced using a polymer reaction after polymerization of fineparticle polymers.

In a case where a cross-linking group is introduced to a polymer at thetime of polymerization of polymer fine particles, it is preferable thata monomer having a cross-linking group may be subjected to an emulsionpolymerization or suspension polymerization. Specific examples of themonomer having a cross-linking group include allyl methacrylate, allylacrylate, vinyl methacrylate, vinyl acrylate, glycidyl methacrylate,glycidyl acrylate, 2-isocyanate ethyl methacrylate or block isocyanateresulting from alcohol thereof, 2-isocyanate ethyl acrylate or blockisocyanate resulting from alcohol thereof, 2-aminoethyl methacrylate,2-aminoethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethylacrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctionalacrylate, and bifunctional methacrylate.

Examples of the polymer reaction used in a case where a cross-linkinggroup is introduced after polymerization of polymer fine particlesinclude polymer reactions described in WO96/34316A.

Polymer fine particles may react with each other through a cross-linkinggroup or the thermoplastic polymer fine particles may react with apolymer compound or a low-molecular weight compound added to the imagerecording layer.

The content of the thermoplastic polymer fine particles is preferably ina range of 50% to 95% by mass, more preferably in a range of 60% to 90%by mass, and particularly preferably in a range of 70% to 85% by masswith respect to the solid content of the image recording layer.

<Other Components>

The image recording layer C may contain other components as necessary.

<Surfactant Having Polyoxyalkylene Group or Hydroxy Group>

As a surfactant having a polyoxyalkylene group (hereinafter, alsoreferred to as a POA group) or a hydroxy group, a surfactant having aPOA group or a hydroxy group may be suitably used, but an anionicsurfactant or a non-ionic surfactant is preferable. Among anionicsurfactants or non-ionic surfactants having a POA group or a hydroxygroup, anionic surfactants or non-ionic surfactants having a POA groupare preferable.

As the POA group, a polyoxyethylene group, a polyoxypropylene group, ora polyoxybutylene group is preferable and a polyoxyethylene group isparticularly preferable.

The average degree of polymerization of an oxyalkylene group ispractically in a range of 2 to 50 and preferably in a range of 2 to 20.

The number of hydroxy groups is practically 1 to 10 and preferably in arange of 2 to 8. Here, the number of terminal hydroxy groups in theoxyalkylene group is not included in the number of hydroxy groups.

(Anionic Surfactant Having POA Group or Hydroxy Group)

The anionic surfactant having a POA group is not particularly limited,and examples thereof include polyoxyalkylene alkyl ether carboxylates,polyoxyalkylene alkyl sulfosuccinates, polyoxyalkylene alkyl ethersulfuric acid ester salts, alkyl phenoxy polyoxyalkylene propylsulfonates, polyoxyalkylene alkyl sulfophenyl ethers, polyoxyalkylenearyl ether sulfuric acid ester salts, polyoxyalkylene polycyclicphenylether sulfuric acid ester salts, polyoxyalkylene styryl phenylether sulfuric acid ester salts, polyoxyalkylene alkyl ether phosphoricacid ester salts, polyoxyalkylene alkyl phenyl ether phosphoric acidester salts, and polyoxyalkylene perfluoroalkyl ether phosphoric acidester salts.

The anionic surfactant having a hydroxy group is not particularlylimited, and examples thereof include hydroxy carboxylates, hydroxyalkyl ether carboxylates, hydroxy alkane sulfonates, fatty acidmonoglyceride sulfuric acid ester salts, and fatty acid monoglycerideacid ester salts.

The content of the surfactant having a POA group or a hydroxy group ispreferably in a range of 0.05% to 15% by mass and more preferably in arange of 0.1% to 10% by mass with respect to the solid content of theimage recording layer.

Hereinafter, specific examples of the surfactant having a POA group or ahydroxy group will be described, but the present invention is notlimited thereto. A surfactant A-12 described below is a trade name ofZonyl FSP and available from Dupont. Further, a surfactant N-11described below is a trade name of Zonyl FSO 100 and available fromDupont.

For the purpose of ensuring coating uniformity of the image recordinglayer, the image recording layer may contain an anionic surfactant thatdoes not have a polyoxyalkylene group or a hydroxy group.

The anion surfactant is not particularly limited as long as theabove-described purpose is achieved. Among the examples of the anionicsurfactants, alkyl benzene sulfonic acid or a salt thereof, alkylnaphthalene sulfonic acid or a salt thereof, (di)alkyl diphenyl ether(di)sulfonic acid or a salt thereof, or alkyl sulfuric acid ester saltis preferable.

The addition amount of the anionic surfactant that does not have apolyoxyalkylene group or a hydroxy group is preferably in a range of 1%to 50% by mass and more preferably in a range of 1% to 30% by mass withrespect to the surfactant which has a polyoxyalkylene group or a hydroxygroup.

Hereinafter, specific examples of the anionic surfactant that does nothave a polyoxyalkylene group or a hydroxy group will be described, butthe present invention is not limited thereto.

Further, for the purpose of coating uniformity of the image recordinglayer, a non-ionic surfactant that does not have a polyoxyalkylene groupor a hydroxy group or a fluorine surfactant may be used. For example,fluorine surfactants described in JP1987-170950A (JP-S62-170950A) arepreferably used.

The image recording layer may contain a hydrophilic resin. Preferredexamples of the hydrophilic resin include resins having hydrophilicgroups such as a hydroxy group, a hydroxyethyl group, a hydroxypropylgroup, an amino group, an aminoethyl group, an aminopropyl group, acarboxy group, a carboxylate group, a sulfo group, a sulfonate group,and a phosphoric acid group.

Specific examples of the hydrophilic resin include gum Arabic, casein,gelatin, a starch derivative, carboxy methyl cellulose and sodium saltthereof, cellulose acetate, sodium alginate, vinyl acetate-maleic acidcopolymers, styrene-maleic acid copolymers, polyacrylic acids and saltsof these, polymethacrylic acids and salts of these, a homopolymer and acopolymer of hydroxy ethyl methacrylate, a homopolymer and a copolymerof hydroxy ethyl acrylate, a homopolymer and a copolymer of hydroxypropyl methacrylate, a homopolymer and a copolymer of hydroxy propylacrylate, a homopolymer and a copolymer of hydroxy butyl methacrylate, ahomopolymer and a copolymer of hydroxy butyl acrylate, polyethyleneglycols, hydroxy propylene polymers, polyvinyl alcohols, hydrolyzedpolyvinyl acetate having a degree of hydrolysis of at least 60% andpreferably at least 80%, polyvinyl formal, polyvinyl butyral, polyvinylpyrrolidone, a homopolymer and a copolymer of acrylamide, a homopolymerand a copolymer of methacrylamide, and a homopolymer and a copolymer ofN-methylol acrylamide.

The weight average molecular weight of the hydrophilic resin ispreferably 2,000 or greater from the viewpoints of obtaining sufficientcoated-film strength or printing durability.

The content of the hydrophilic resin is preferably in a range of 0.5% to50% by mass and more preferably in a range of 1% to 30% by mass withrespect to the solid content of the image recording layer.

The image recording layer may contain inorganic fine particles.Preferred examples of the inorganic fine particles include silica,alumina, magnesium oxide, titanium oxide, magnesium carbonate, calciumalginate, and a mixture of these. The inorganic fine particles can beused for the purpose of improving coated-film strength.

The average particle diameter of the inorganic fine particles ispreferably in a range of 5 nm to 10 μm and more preferably in a range of10 nm to 1 μm. When the average particle diameter thereof is in theabove described range, the thermoplastic polymer fine particles arestably dispersed, the film hardness of the image recording layer issufficiently held, and a non-image portion with excellent hydrophilicityin which printing stain is unlikely to occur can be formed.

The inorganic fine particles are available as commercial products suchas a colloidal silica dispersion and the like.

The content of the inorganic fine particles is preferably in a range of1.0% to 70% by mass and more preferably in a range of 5.0% to 50% bymass with respect to the solid content of the image recording layer.

The image recording layer may contain a plasticizer in order to provideflexibility for a coated film. Examples of the plasticizer includepolyethylene glycol, tributyl citrate, diethyl phthalate, dibutylphthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate,tributyl phosphate, trioctyl phosphate, and tetrahydrofurfuryl oleate.

The content of the plasticizer is preferably in a range of 0.1% to 50%by mass and more preferably in a range of 1% to 30% by mass with respectto the solid content of the image recording layer.

In a case where polymer fine particles having a thermally reactivefunctional group (cross-linking group) are used for the image recordinglayer, a compound that starts or promotes a reaction of the thermallyreactive functional group (cross-linking group) can be added to theimage recording layer as necessary. As the compound that starts orpromotes a reaction of the thermally reactive functional group, acompound that generates a radical or a cation by heating may beexemplified. Examples of the compound include a lophine dimer, atrihalomethyl compound, a peroxide, an azo compound, onium saltsincluding diazonium salts and diphenyl iodonium salts, acyl phosphine,and imide sulfonate. The amount of the compound to be added to the imagerecording layer is preferably in a range of 1% to 20% by mass and morepreferably in a range of 1% to 10% by mass with respect to the solidcontent of the image recording layer. When the amount thereof is in theabove-described range, on-press developability is not degraded andexcellent effects for starting or promoting a reaction are obtained.

<Formation of Image Recording Layer C>

The image recording layer C is formed by dissolving or dispersing eachof the above-described required components in a suitable solvent toprepare a coating solution, coating a support with the coating solutiondirectly or through an undercoat layer. As the solvent, water or a mixedsolvent of water and an organic solvent is used, and a mixed solvent ofwater and an organic solvent is preferable from the viewpoint of theexcellent surface state after coating. Since the amount of the organicsolvent varies depending on the type of organic solvent, the amountthereof cannot be specified unconditionally, but the amount of theorganic solvent in the mixed solvent is preferably in a range of 5% to50% by volume. Here, it is necessary that the amount of the organicsolvent to be used is set such that the thermoplastic polymer fineparticles are not aggregated. The concentration of solid contents of theimage recording layer coating solution is preferably in a range of 1% to50% by mass.

As the organic solvent used as a solvent of the coating solution, awater-soluble organic solvent is preferable. Specific examples thereofinclude an alcohol solvent such as methanol, ethanol, propanol,isopropanol, or 1-methoxy-2-propanol, a ketone solvent such as acetoneor methyl ethyl ketone, a glycol ether solvent such as ethylene glycoldimethyl ether, γ-butyrolactone, N,N-dimethylformamide,N,N-dimethylacetamide, tetrahydrofuran, and dimethylsulfoxide.Particularly, an organic solvent having a boiling point of 120° C. orlower and a solubility (amount of a solvent to be dissolved in 100 g ofwater) of 10 g or greater in water is preferable and an organic solventhaving a solubility of 20 g or greater is more preferable.

As a coating method of the image recording layer coating solution,various methods can be used. Examples of the methods include a barcoater coating method, a rotary coating method, a spray coating method,a curtain coating method, a dip coating method, an air knife coatingmethod, a blade coating method, and a roll coating method. The coatingamount (solid content) of the image recording layer on the supportobtained after the coating and the drying varies depending on thepurpose thereof, but is preferably in a range of 0.5 to 5.0 g/m² andmore preferably in a range of 0.5 to 2.0 g/m².

Hereinafter, other constituent elements of the lithographic printingplate precursor will be described.

[Undercoat Layer]

The lithographic printing plate precursor may be provided with anundercoat layer between the image recording layer and the support asnecessary. Since bonding of the support to the image recording layerbecomes stronger in an exposed portion and the support is easilyseparated from the image recording layer in an unexposed portion, theundercoat layer contributes to improvement of the on-pressdevelopability without degrading the printing durability. Further, in acase of infrared layer exposure, the undercoat layer functions as a heatinsulating layer so that a degradation in sensitivity due to heat,generated by exposure, being diffused in the support is prevented.

Examples of eth compound used for the undercoat layer include a silanecoupling agent having an ethylenic double bond reaction group, which canbe added and polymerized, described in JP1998-282679A (JP-H10-282679A);and a phosphorous compound having an ethylenic double bond reactiongroup described in JP1990-304441A (JP-H02-304441A). Preferred examplesthereof include polymer compounds having an adsorptive group which canbe adsorbed to the surface of the support, a hydrophilic group, and across-linking group, as described in JP2005-125749A and JP2006-188038A.As such a polymer compound, a copolymer of a monomer having anadsorptive group, a monomer having a hydrophilic group, and a monomerhaving a cross-linking group is preferable. Specific examples thereofinclude a copolymer of a monomer having an adsorptive group such as aphenolic hydroxy group, a carboxy group, —PO₃H₂, —OPO₃H₂, —CONHSO₂—,—SO₂NHSO₂—, or —COCH₂COCH₃, a monomer having a hydrophilic group such asa sulfo group, and a monomer having a polymerizable cross-linking groupsuch as a methacryl group or an allyl group. The polymer compound mayinclude a cross-linking group introduced by forming salts between apolar substituent of the polymer compound and a compound that includes asubstituent having the opposite charge and an ethylenic unsaturatedbond. Further, monomers other than the monomers described above,preferably hydrophilic monomers may be further copolymerized.

The content of the unsaturated double bond in the polymer compound foran undercoat layer is preferably in a range of 0.1 to 10.0 mmol and morepreferably in a range of 2.0 to 5.5 mmol with respect to 1 g of thepolymer compound.

The weight-average molecular weight of the polymer compound for anundercoat layer is preferably 5,000 or greater and more preferably in arange of 10,000 to 300,000.

For the purpose of preventing stain over time, the undercoat layer maycontain a chelating agent, a secondary or tertiary amine, apolymerization inhibitor, an amino group, a compound that includes anamino group or a functional group having polymerization inhibitingability and a group interacting with the surface of an aluminum support,and the like (for example, 1,4-diazabicyclo[2,2,2]octane (DABCO),2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid,hydroxyethyl ethylene diamine triacetic acid, dihydroxyethyl ethylenediamine diacetic acid, or hydroxyethyl imino diacetic acid) in additionto the compounds for an undercoat layer described above.

The undercoat layer is applied according to a known method. The coatingamount (solid content) of the undercoat layer is preferably in a rangeof 0.1 to 100 mg/m² and more preferably in a range of 1 to 30 mg/m².

[Support]

A known support is used as the support of the lithographic printingplate precursor. Among examples of the known support, an aluminum platesubjected to a roughening treatment and an anodizing treatment using aknown method is preferable.

The aluminum plate can be subjected to a treatment appropriatelyselected from an expansion treatment or a sealing treatment ofmicropores of an anodized film described in JP2001-253181A orJP2001-322365A or a surface hydrophilization treatment using alkalimetal silicate described in U.S. Pat. Nos. 2,714,066A, 3,181,461A,3,280,734A, and 3,902,734A or polyvinyl phosphonic acid described inU.S. Pat. Nos. 3,276,868A, 4,153,461A, and 4,689,272A as necessary.

The center line average roughness of the support is preferably in arange of 0.10 to 1.2 μm.

The rear surface of the support may be provided with an organic polymercompound described in JP1993-45885A (JP-H05-45885A) and a back coatlayer containing an alkoxy compound of silicon described inJP1994-35174A (JP-H06-35174A) as necessary.

[Protective Layer]

A protective layer may be provided on the image recording layer of theprecursor as necessary. The protective layer has a function ofsuppressing a reaction of inhibiting image formation through oxygenblocking, a function of preventing generation of damage to the imagerecording layer, and a function of preventing ablation at the time ofhigh illuminance laser exposure.

As the protective layer having such functions, a protective layerdescribed in paragraphs [0202] to [0204] of JP2014-104631A can be usedand the contents of which are incorporated in the specification of thepresent application.

The protective layer is applied according to a known method. The coatingamount of the protective layer after the drying is preferably in a rangeof 0.01 to 10 g/m², more preferably in a range of 0.02 to 3 g/m², andparticularly preferably in a range of 0.02 to 1 g/m².

[Method of Producing Lithographic Printing Plate Precursor]

As described above, the end portion regions of the lithographic printingplate precursor of the present invention contain the specific polymerwith a higher content than those of other regions. The method ofproducing a lithographic printing plate precursor is not particularlylimited as long as a lithographic printing plate precursor having such aconfiguration is obtained. Hereinafter, the method of producing alithographic printing plate precursor according to the present inventionwill be described.

The specific polymer can be introduced to the end portion regions of thelithographic printing plate precursor by applying a coating solutioncontaining the specific polymer to the end portion regions of thelithographic printing plate precursor during the step of producing thelithographic printing plate precursor. The coating solution containingthe specific polymer may be applied to the end portion regions of thelithographic printing plate precursor at any timing of the step ofproducing the lithographic printing plate precursor, and it ispreferable that the coating solution is applied thereto before and afterthe step of forming each configuration layer, that is, before thecoating of the lowermost layer (for example, the undercoat layer) toafter the drying of the uppermost layer (for example, the protectivelayer). The lithographic printing plate precursor may be cut before orafter the coating solution containing the specific polymer is applied tothe end portion regions of the lithographic printing plate precursor.

In other words, in the step of forming each configuration layer of thelithographic printing plate, the lithographic printing plate precursormay be cut such that the end portion regions of the lithographicprinting plate precursor are formed after the coating solutioncontaining the specific polymer is applied to positions corresponding tothe end portion regions of the lithographic printing plate precursor.Alternatively, the coating solution containing the specific polymer maybe applied to the end portion regions of the lithographic printing plateprecursor after the lithographic printing plate precursor produced byperforming the step of forming each configuration layer of thelithographic printing plate precursor is cut. Here, the positionscorresponding to the end portion regions indicate positions in whichregions on the plate surface on the image recording layer side from theend portion to a portion inside the end portion by 5 mm of the cutlithographic printing plate precursor can be formed. Accordingly, thepositions corresponding to the end portion regions may be positions inthe vicinity of the ends of the lithographic printing plate precursor orpositions in the vicinity of the center of the lithographic printingplate precursor in the step of producing the lithographic printing plateprecursor. In a case where the positions are positions in the vicinityof the center of the lithographic printing plate precursor, two sheetsof lithographic printing plate precursors having end portion regions areobtained by cutting the lithographic printing plate precursor such thatthe end portion regions are formed along the region coated with thespecific polymer.

As an embodiment in which the lithographic printing plate precursor iscut such that the end portion regions thereof are formed after thecoating solution containing the specific polymer is applied to thepositions corresponding to the end portion regions of the lithographicprinting plate precursor in the step of forming each configuration layerof the lithographic printing plate precursor, for example, the followingmethod may be preferably exemplified.

In a lithographic printing plate precursor including a support and animage recording layer on the support, a method of producing alithographic printing plate precursor of performing an image recordinglayer forming step a of forming the image recording layer; a coatingstep b of coating a part of a region of the image recording layer whichis formed by the step a with a coating solution containing the specificpolymer such that the coating solution and the region overlap eachother; and a cutting step c of cutting the region coated with thecoating solution to be in a range on the plate surface on the imagerecording layer side from the end portion of the cut lithographicprinting plate precursor to a portion inside the end portion by 5 mm, inorder of the step a, the step b, and then the step c or in order of thestep b, the step a, and then the step c, on the support, is exemplified.

Further, a protective layer forming step e of forming a protective layermay be performed on the image recording layer after the step a andbefore the step c.

In a lithographic printing plate precursor including a support, and anundercoat layer and an image recording layer provided on the support inthis, order, a method of producing a lithographic printing plateprecursor of performing an image recording layer forming step a offorming the image recording layer; a coating step b of coating a part ofa region of the image recording layer which is formed by the step a witha coating solution containing the specific polymer such that the coatingsolution and the region overlap each other; a cutting step c of cuttingthe region coated with the coating solution to be in a range on theplate surface on the image recording layer side from the end portion ofthe cut lithographic printing plate precursor to a portion inside theend portion by 5 mm; and an undercoat layer forming step d of formingthe undercoat layer, in order of the step b, the step d, the step a, andthen the step c, in order of the step d, the step b, the step a, andthen the step c, or in order of the step d, the step a, the step b, andthen the step c, on the support, is exemplified.

In a lithographic printing plate precursor including a support, and anundercoat layer, an image recording layer and a protective layerprovided on the support in this order, a method of producing alithographic printing plate precursor of performing an image recordinglayer forming step a of forming the image recording layer; a coatingstep b of coating a part of a region of the image recording layer whichis formed by the step a with a coating solution containing the specificpolymer such that the coating solution and the region overlap eachother; a cutting step c of cutting the region coated with the coatingsolution to be in a range on the plate surface on the image recordinglayer side from the end portion of the cut lithographic printing plateprecursor to a portion inside the end portion by 5 mm; an undercoatlayer forming step d of forming the undercoat layer; and a protectivelayer forming step e of forming a protective layer, in order of the stepb, the step d, the step a, the step e, and then the step c, in order ofthe step d, the step b, the step a, the step e, and then the step c, inorder of the step d, the step a, the step b, the step e, and then thestep c, or in order of the step d, the step a, the step e, the step b,and then the step c, on the support, is exemplified.

As an embodiment in which the coating solution containing the specificpolymer is applied to the end portion regions of the lithographicprinting plate precursor after the lithographic printing plate precursorproduced by performing a step of forming each configuration layer of thelithographic printing plate precursor is cut, for example, the followingmethod may be preferably exemplified.

In a lithographic printing plate precursor including a support and animage recording layer on the support, a method of producing alithographic printing plate precursor of performing an image recordinglayer forming step a of forming the image recording layer; and a coatingstep f of coating a region on the plate surface on the image recordinglayer side, from the end portion of the lithographic printing plateprecursor to a portion inside the end portion by 5 mm, with a coatingsolution containing the specific polymer, in order of the step a and thestep f on the support, is exemplified.

Further, a protective layer forming step e of forming a protective layermay be performed on the image recording layer after the step a andbefore the step f.

In a lithographic printing plate precursor including a support, and anundercoat layer and an image recording layer provided on the support inthis order, a method of producing a lithographic printing plateprecursor of performing an image recording layer forming step a offorming the image recording layer; a coating step f of coating a regionon the plate surface of the image recording layer side, from the endportion of the lithographic printing plate precursor to a portion insidethe end portion by 5 mm, with a coating solution containing the specificpolymer; and an undercoat layer forming step d of forming the undercoatlayer, in order of the step d, the step a, and the step f on the supportis exemplified.

In a lithographic printing plate precursor including a support, and anundercoat layer, an image recording layer and a protective layerprovided on the support in this order, a method of producing alithographic printing plate precursor of performing an image recordinglayer forming step a of forming the image recording layer; a coatingstep f of coating a region on the plate surface on the image recordinglayer side, from the end portion of the lithographic printing plateprecursor to a portion inside the end portion by 5 mm, with a coatingsolution containing the specific polymer; an undercoat layer formingstep d of forming the undercoat layer; and a protective layer formingstep e of forming a protective layer, in order of the step d, the stepa, the step e, and the step f on the support is exemplified.

The step of forming the configuration layer includes at least a step ofcoating the configuration layer. A step of drying the coated layer aftercoating the configuration layer is not necessarily required for the stepof forming the configuration layer. For example, the support is coatedwith an undercoat layer and then coated with a coating solutioncontaining the specific polymer without drying the coated layer. In thiscase, it is considered that the specific polymer is present not only onthe undercoat layer and but also in the undercoat layer.

[Specific Polymer-Containing Coating Solution]

The specific polymer-containing coating solution is a coating solutioncontaining the specific polymer described above. It is preferable thatthe specific polymer-containing coating solution is in the form of anaqueous solution in which the specific polymer is dissolved in a mediummainly formed of water.

It is preferable that the specific polymer-containing coating solutioncontains the above-described hydrophilic compound. The content of thehydrophilic compound in the specific polymer-containing coating solutionis preferably in a range of 0.03% to 20.0% by mass and more preferablyin a range of 0.05% to 10% by mass with respect to the total mass of thespecific polymer-containing coating solution.

It is preferable that the specific polymer-containing coating solutionmay contain a water-soluble resin other than the specific polymers.Similar to the above-described specific polymers, the water-solubleresin has an effect of hydrophilizing cracks which can be generated atthe time when a shear drop shape described below is formed andpreventing stain generated due to accumulation of printing ink in thecracks. Examples of the water-soluble resin include water-soluble resinsclassified as polysaccharides, polyvinyl alcohol, polyvinyl pyrrolidone,polyacrylamide, and a copolymer of these, a vinyl methyl ether-maleicanhydride copolymer, a vinyl acetic acid-maleic anhydride copolymer, anda styrene-maleic anhydride copolymer.

Examples of the polysaccharides include starch derivatives (such asdextrin, enzymatically decomposed dextrin, hydroxypropylated starch,carboxymethylated starch, phosphoric acid esterified starch,polyoxyalkylene grafted starch, and cyclodextrin); celluloses (such ascarboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose,hydroxypropyl cellulose, and methylpropyl cellulose); carrageenan,alginic acid, guar gum, locust bean gum, xanthan gum, gum Arabic, andsoybean polysaccharides.

Among the water-soluble resins, starch derivatives such as dextrin andpolyoxyalkylene grafted starch, gum Arabic, carboxymethyl cellulose, andsoybean polysaccharides are preferably used.

The water-soluble resin may be used in combination of two or more kindsthereof. The content of the water-soluble resin is preferably in a rangeof 0.5% to 30% by mass and more preferably in a range of 1% to 10% bymass with respect to the total mass of the specific polymer-containingcoating solution. When the content thereof is in the above-describedrange, the effects of the water-soluble resin are achievedsatisfactorily.

The specific polymer-containing coating solution may further contain asurfactant, an organic solvent, a plasticizer, and other additives.

(Surfactant)

Examples of the surfactant used for the specific polymer-containingcoating solution include anionic surfactants, non-ionic surfactants,cationic surfactants, and amphoteric surfactants. Among these, anionicsurfactants and non-ionic surfactants are preferable. The surfactantcontributes to adjustment of coating properties of the specificpolymer-containing coating solution.

Examples of the anionic surfactant include compounds described inparagraph of [0022] of JP2014-104631A and the contents of which areincorporated in the specification of the present application.

Among the above-described anionic surfactants, dialkyl sulfosuccinates,alkyl sulfonic acid ester salts, polyoxyethylene aryl ether sulfonicacid ester salts, and alkyl naphthalene sulfonates are preferable.

Specifically, anionic surfactants represented by the following Formula(I-A) or (I-B) may be exemplified.

In Formula (I-A), R¹ represents a linear or branched alkyl group having1 to 20 carbon atoms; p represents 0, 1, or 2; Ar¹ represents an arylgroup having 6 to 10 carbon atoms; q represents 1, 2, or 3; and M₁ ⁺represents Na⁺, K⁺, Li⁺, or NH₄ ⁺. When p represents 2, a plurality ofR¹'s may be the same as or different from each other.

In Formula (I-B), R² represents a linear or branched alkyl group having1 to 20 carbon atoms; m represents 0, 1, or 2; Ar² represents an arylgroup having 6 to 10 carbon atoms; Y represents a single bond or analkylene group having 1 to 10 carbon atoms; R³ represents a linear orbranched alkylene group having 1 to 5 carbon atoms; n represents aninteger of 1 to 100; and M₂ ⁺ represents Na⁺, K⁺, Li⁺, or NH₄ ⁺. When mrepresents 2, a plurality of R²'s may be the same as or different fromeach other. When n represents 2 or greater, a plurality of R³'s may bethe same as or different from each other.

In Formulae (I-A) and (I-B), preferred examples of R¹ and R² includeCH₃, C₂H₅, C₃H₇, and C₄H₉. Further, preferred examples of R³ include—CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, and —CH₂CH(CH₃)—. Among these, —CH₂CH₂— ismore preferable. Moreover, it is preferable that p and m represent 0 or1 and particularly preferable that p represents 0. It is preferable thatY represents a single bond. Further, it is preferable that n representsan integer of 1 to 20.

Specific examples of the anionic surfactants represented by Formula(I-A) or (I-B) include the following compounds.

Examples of the non-ionic surfactant include compounds described inparagraph of [0031] of JP2014-104631A and the contents of which areincorporated in the specification of the present application.

Among the above-described non-ionic surfactants, polyoxyethylene arylethers and polyoxyethylene-polyoxypropylene block copolymers arepreferable.

Specific preferred examples include non-ionic surfactants represented bythe following Formula (II-A).

(R⁴)_(s)—Ar³—O(CH₂CH₂O)_(t)(CH₂CH(CH₃)O)_(u)H  (II-A)

In Formula (II-A), R⁴ represents a hydrogen atom or an alkyl grouphaving 1 to 20 carbon atoms, s represents 0, 1, or 2, Ar³ represents anaryl group having 6 to 10 carbon atoms, and t and u each independentlyrepresent an integer of 0 to 100 and either of t and u does notrepresent 0. In a case where s represents 2, a plurality of R⁴'s may bethe same as or different from each other.

Examples of the compound represented by Formula (II-A) includepolyoxyethylene phenyl ether, polyoxyethylene methyl phenyl ether,polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether,polyoxyethylene naphthyl ether, polyoxyethylene methyl naphthyl ether,polyoxyethylene octyl naphthyl ether, and polyoxyethylene nonyl naphthylether.

In the compounds represented by Formula (II-A), the number (t) ofrepeating units of the polyoxyethylene chain is preferably in a range of2 to 50 and more preferably in a range of 4 to 30. The number (u) ofrepeating units of the polyoxypropylene chain is preferably in a rangeof 0 to 10 and more preferably in a range of 0 to 5. The polyoxyethyleneportion and the polyoxypropylene portion may be present randomly or inthe form of a block.

Specific examples of the non-ionic surfactant represented by Formula(II-A) are described below. An oxyethylene repeating unit and anoxypropylene repeating unit in the compound “Y-5” exemplified below maybe in the form of any of a random bond and block connection.

The surfactant may be used in combination of two or more kinds thereof.Examples thereof include a combination of two or more kinds of anionicsurfactants different from each other, a combination of two or morekinds of non-ionic surfactants different from each other, and acombination of an anionic surfactant and a non-ionic surfactant.

The content of the surfactant in the specific polymer-containing coatingsolution is preferably in a range of 0.01% to 20% by mass and morepreferably in a range of 0.1% to 15% by mass with respect to the totalmass of the coating solution.

(Organic Solvent)

An organic solvent may be contained for the purpose of adjusting thesolubility of the water-soluble resin and promoting swelling of theimage recording layer. Examples of the organic solvent include analcohol-based solvent, a ketone-based solvent, an ester-based solvent,an amide-based solvent, and a hydrocarbon-based solvent. Among theorganic solvents, an alcohol-based solvent is preferably used.

Examples of the alcohol-based solvent include methyl alcohol, n-propylalcohol, iso-propyl alcohol, n-butyl alcohol, tert-butyl alcohol, n-amylalcohol, diacetone alcohol, 1-methoxy-2-propanol, furfuryl alcohol,2-octanol, 2-ethylhexanol, nonanol, n-decanol, undecanol, n-dodecanol,trimethyl nonyl alcohol, benzyl alcohol, phenethyl alcohol, ethyleneglycol monoisoamyl ether, ethylene glycol monophenyl ether, ethyleneglycol monobenzyl ether, and ethylene glycol monohexyl ether. Amongthese, benzyl alcohol, phenethyl alcohol, and furfuryl alcohol arepreferable.

The organic solvent may be used in combination of two or more kindsthereof. The content of the organic solvent is preferably in a range of0.5% to 10% by mass and more preferably in a range of 1% to 5% by masswith respect to the total mass of the specific polymer-containingcoating solution. When the content thereof is in the above-describedrange, the effects of the organic solvent are achieved satisfactorily.

(Plasticizer)

Examples of the plasticizer include plasticizers having a freezing pointof 15° C. or lower, for example, phthalic acid diesters such as dibutylphthalate, diheptyl phthalate, di-n-octyl phthalate, di(2-ethylhexyl)phthalate, dinonyl phthalate, didecyl phthalate, dilauryl phthalate, andbutyl benzyl phthalate; aliphatic dibasic acid esters such as dioctyladipate, butyl glycol adipate, dioctyl azelate, dibutyl sebacate,di(2-ethylhexyl) sebacate, and dioctyl sebacate; epoxidizedtriglycerides such as epoxidized soybean oil; phosphoric acid esterssuch as tricresyl phosphate, trioctyl phosphate, and trischloroethylphosphate; and benzoic acid esters such as benzyl benzoate.

The plasticizer may be used in combination of two or more kinds thereof.The content of plasticizer is preferably in a range of 0.5% to 10% bymass and more preferably in a range of 1% to 5% by mass with respect tothe total mass of the specific polymer-containing coating solution.

(Other Additives)

The specific polymer-containing coating solution may containwater-soluble inorganic salts such as nitrate and sulfate, water-solubleorganic compounds such as a polyol, a betaine, organic sulfonate,organic sulfate, organic carboxylate, and amino acid, a preservative,and an anti-foaming agent in addition to the above-described components.

Examples of the inorganic salts include magnesium nitrate, sodiumnitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassiumsulfate, ammonium sulfate, sodium hydrogen sulfate, and nickel sulfate.

Examples of the inorganic salts include magnesium nitrate, sodiumnitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassiumsulfate, ammonium sulfate, sodium hydrogen sulfate, and nickel sulfate.

The polyol includes an aliphatic polyol compound, an alicyclic polyolcompound, and a nitrogen-containing heterocyclic polyol compound.

The number of hydroxy groups in a molecule of the polyol is practicallyin a range of 2 to 6 and preferably in a range of 3 to 6.

Examples of the aliphatic polyol compound include ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol, propyleneglycol, neopentyl glycol, 1,3-butylene glycol, 1,4-butanediol,1,5-pentanediol, cis-2-butene-1,4-diol, trans-2-butene-1,4-diol,di-1,2-propylene glycol, di-1,3-propylene glycol, tri-1,3-propyleneglycol, glycerin, 1,1,1-trimethylolpropane, hexanetriol,pentaerythritol, sorbitol, hydroxy polyesters obtained from polyvalentcarboxylic acid and polyhydric alcohol, and hydroxy polyalkylene etherwhich is a condensate of polyhydric alcohol and alkylene oxide.

Examples of the alicyclic polyol compound include cyclohexane dimethanoland inositol.

Examples of the nitrogen-containing heterocyclic polyol compound includetris(2-hydroxyethyl)isocyanurate and 1,4-bis(2-hydroxyethyl)piperazine.

Among the examples of the polyol, an aliphatic polyol compound and anitrogen-containing heterocyclic polyol compound are preferable and analiphatic polyol compound is particularly preferable.

As the betaine, a betaine compound having 1 to 5 carbon atoms of ahydrocarbon group bonded to nitrogen atoms is preferable. Specificexamples thereof include trimethyl ammonium acetate, dimethyl propylammonium acetate, 3-hydroxy-4-trimethylammoniobutylate,4-(1-pyridinio)butyrate, 1-hydroxyethyl-1-imidazolioacetate, trimethylammonium methane sulfonate, dimethyl propyl ammonium methane sulfonate,3-trimethylammonio-1-propanesulfonate, and3-(1-pyridinio)-1-propanesulfonate.

As the organic sulfonate, a compound including organic sulfamate andhaving 1 to 8 carbon atoms is preferable and a compound includingorganic sulfamate and having 1 to 5 carbon atoms is more preferable. Analkali metal salt (a sodium salt, a potassium salt, or a lithium salt)is preferable as a salt. Specific examples of the organic sulfonateinclude sodium methanesulfonate, sodium n-butyl sulfonate, sodiumisobutyl sulfonate, sodium sec-butyl sulfonate, sodium tert-butylsulfonate, sodium n-pentyl sulfonate, sodium 1,2-dimethyl propylsulfonate, sodium 1-ethyl propyl sulfonate, sodium n-hexyl sulfonate,sodium 2-ethyl butyl sulfonate, sodium cyclohexyl sulfonate, sodiumn-heptyl sulfonate, sodium allyl sulfonate, sodium 2-methyl allylsulfonate, sodium n-butyl sulfamate, sodium isobutyl sulfamate, sodiumtert-butyl sulfamate, sodium n-pentyl sulfamate, sodium 1,2-dimethylpropyl sulfamate, sodium 1-ethyl propyl sulfamate, sodium n-hexylsulfamate, sodium 2-ethyl butyl sulfamate, and sodium cyclohexylsulfamate. The sodium salt in the above-described specific examples maybe a potassium salt or a lithium salt.

As the organic sulfate, a compound having 1 to 7 carbon atoms ispreferable and a compound having 1 to 5 carbon atoms is more preferable.The organic sulfate includes an alkyl, alkenyl, or alkynyl ofpolyethylene oxide or a sulfate of heterocyclic monoether. The number ofethylene oxide units is preferably in a range of 1 to 4. As a salt, analkali metal salt (a sodium salt, a potassium salt, or a lithium salt)is preferable. Specific examples of the organic sulfate include sodium2-methoxy ethyl sulfate.

As the organic carboxylate, a compound having 1 to 6 carbon atoms ispreferable and a compound having 1 to 4 carbon atoms is more preferable.In this case, the number of carbon atoms does not include the number ofcarbon atoms of a carboxy group. As the salt thereof, an alkali metalsalt (a sodium salt, a potassium salt, or a lithium salt) is preferable.Among the alkali metal salts, a sodium salt or a potassium salt ispreferable and a sodium salt is more preferable. Examples of the organiccarboxylic acid include aliphatic monocarboxylic acid such as formicacid, acetic acid, propionic acid, butyric acid, valeric acid, caproicacid, or enanthic acid; unsaturated aliphatic monocarboxylic acid suchas crotonic acid; aliphatic dicarboxylic acid such as oxalic acid,succinic acid, adipic acid, or maleic acid; oxycarboxylic acid such asglycolic acid, lactic acid, gluconic acid, malic acid, tartaric acid, orcitric acid; and polycarboxylic acid such as ethylene tetracarboxylicacid. Among the examples of the organic carboxylic acid, monocarboxylicacid, dicarboxylic acid or oxycarboxylic acid is preferable anddicarboxylic acid or oxycarboxylic acid is more preferable.

As the organic carboxylate, an alkali metal salt of the above-describedcarboxylic acid is preferable. An alkali metal salt of monocarboxylicacid, dicarboxylic acid, or oxycarboxylic acid is more preferable and analkali metal salt of dicarboxylic acid or oxycarboxylic acid isparticularly preferable. Specific examples of the organic carboxylateinclude sodium formate, sodium acetate, sodium propionate, sodiumcrotonate, disodium oxalate, disodium succinate, disodium adipate,disodium maleate, sodium glycolate, sodium lactate, sodium gluconate,disodium malate, disodium tartrate, potassium sodium tartrate,monosodium citrate, disodium citrate, and trisodium citrate.

The amino acid includes a so-called amino acid having a carboxy groupand an amino group in the same molecule and an N-substitute formed byintroducing a hydrocarbon group to an amino acid.

Specific examples of the amino acid include glycine, alanine, β-alanine,valine, leucine, norleucine, threonine, methionine, cysteine,γ-aminobutyric acid, asparagine, hydroxylysine, arginine, and histidine.

The hydrocarbon group which can be introduced to an N-substitute of anamino acid is a hydrocarbon group having 3 or less carbon atoms, andexamples thereof include an alkyl group such as a methyl group, an ethylgroup, a propyl group, or an isopropyl group. Specific examples of theN-substitute formed by introducing a hydrocarbon group to an amino acidinclude sarcosine and N,N-dimethyl glycine.

Examples of the preservative include phenol or a derivative thereof,formalin, an imidazole derivative, sodium dehydroacetate, a4-isothiazolin-3-one derivative, benzoisothiazolin-3-one, abenzotriazole derivative, an amidine guanidine derivative, derivativesof quaternary ammonium salts, pyridine, quinoline, and guanidine,diazine, a triazole derivative, oxazole, an oxazine derivative, andnitro bromo alcohol-based 2-bromo-2-nitropropane-1,3-diol,1,1-dibromo-1-nitro-2-ethanol, and 1,1-dibromo-1-nitro-2-propanol.

Examples of the anti-foaming agent include a typical silicon-basedself-emulsification type non-ionic surfactant, an emulsification typenon-ionic surfactant, and a non-ionic surfactant having an HLB of 5 orless.

<Preparation of Specific Polymer-Containing Coating Solution>

The specific polymer-containing coating solution is prepared by addingthe specific polymer and additives used as necessary to water (distilledwater, ion exchange water, or demineralized water).

The content of the specific polymer in the specific polymer-containingcoating solution is preferably in a range of 0.05% to 50% by mass, morepreferably in a range of 0.1% to 30% by mass, and particularlypreferably in a range of 0.2% to 10% by mass.

The viscosity of the specific polymer-containing coating solution at 25°C. is preferably in a range of 0.5 to 1,000 mPa·s and more preferably ina range of 1 to 100 mPa·s. From the viewpoints that bead breakage isunlikely to occur and the coating at the time of starting application issmoothly carried out, it is preferable that the viscosity thereof is inthe above-described range.

The surface tension of the specific polymer-containing coating solutionat 25° C. is preferably in a range of 25 to 70 mN/m and more preferablyin a range of 40 to 65 mN/m. From the viewpoints that the coating widthis easily controlled and bead breakage is unlikely to occur, it ispreferable that the surface tension thereof is in the above-describedrange.

[Application of Specific Polymer-Containing Coating Solution]

As described above, the specific polymer-containing coating solution isapplied to positions corresponding to the end portion regions in thestep of production of the lithographic printing plate precursor. Thecoating width is preferably a region from an end portion or a positioncorresponding to the end portion to a portion inside the end portion by5 mm and more preferably a region from an end portion or a positioncorresponding to the end portion to a portion inside the end portion by3 mm.

The specific polymer-containing coating solution can be applied usingknown methods such as a die coating method, a dip coating method, an airknife coating method, a curtain coating method, a roller coating method,a wire bar coating method, a gravure coating method, a slide coatingmethod, an ink-jet method, a dispenser method, and a spray method. Fromthe viewpoint of applying the coating solution to a specific position,an ink-jet method or a dispenser method is preferable.

According to the embodiment in which the specific polymer-containingcoating solution is applied after the lithographic printing plateprecursor is cut, a coating method of using cloth or a Molton rollimpregnated with the specific polymer-containing coating solution can beused in addition to the above-described coating methods.

The coating amount of the specific polymer-containing coating solutionis preferably in a range of 0.05 to 5.0 g/m² and more preferably in arange of 0.1 to 2.0 g/m² as a solid content after drying.

The specific polymer-containing coating solution is applied and thendried. The drying may be performed after the specific polymer-containingcoating solution is applied or after the lithographic printing plateprecursor is coated with a coating solution for forming a configurationlayer.

The drying may be performed by blowing dry air using an oven. The dryingtemperature is preferably in a range of 60° C. to 250° C. and morepreferably in a range of 80° C. to 160° C.

[Cutting of Lithographic Printing Plate Precursor]

The lithographic printing plate precursor is cut during the step ofproduction of the lithographic printing plate precursor as describedabove. The cutting may be performed using known cutting methods.Preferred examples thereof include methods described in JP1996-58257A(JP-H08-58257A), JP1997-211843A (JP-H09-211843A), JP1998-100556A(JP-H10-100556A), and JP1999-52579A (JP-H11-52579A).

It is preferable that the end portions of the lithographic printingplate precursor have a shear drop shape. The lithographic printing plateprecursor having end portions in a shear drop shape has excellenteffects of preventing edge stain together with the specificpolymer-containing end portion regions of the present invention.

FIG. 1 is a view schematically illustrating the cross-sectional shape ofa lithographic printing plate precursor.

In FIG. 1, a lithographic printing plate precursor 1 includes a sheardrop 2 in the end portion thereof. A distance X between the upper end(boundary point between the shear drop 2 and the end surface 1 c) of anend surface 1 c of the lithographic printing plate precursor 1 and theextension line of an image recording layer surface (protective layersurface in a case where a protective layer is formed) 1 a is referred toas an “amount of shear drop” and a distance Y between the starting pointof shear drop of the image recording layer surface 1 a of thelithographic printing plate precursor 1 and the extension line of theend surface 1 c is referred to as a “width of shear drop”. The amount ofshear drop of the end portion of the lithographic printing plateprecursor is preferably 35 μm or greater and more preferably 40 μm orgreater. From the viewpoint of preventing degradation of on-pressdevelopability caused by deterioration in the surface state of the endportion, the upper limit of the amount of shear drop is preferably 150μm. When the on-press developability is degraded, ink is adhered to theremaining image recording layer and, as the result, edge stain isgenerated. When the amount of shear drop is less than 35 μm, the inkadhering to the end portion is easily transferred to a blanket and thismay cause edge stain. In a case where the amount of shear drop is in arange of 35 to 150 μm, when the width of shear drop is small, cracks aregenerated in the end portion so that printing ink is accumulated in thecracks, and this leads to generation of edge stain. In order to decreasethe generation of cracks, the width of shear drop is practically in arange of 70 to 300 μm and preferably in a range of 80 to 250 μm.Further, the preferable ranges of the amount of shear drop and the widthof shear drop are not relevant to the edge shape of a support surface 1b of the lithographic printing plate precursor 1.

Similar to the image recording layer surface 1 a, the shear drop isgenerated typically in a boundary B between the image recording layerand the support, and the support surface 1 b in end portions of thelithographic printing plate precursor 1.

An end portion having the shear drop can be formed by adjusting theconditions of cutting the lithographic printing plate precursor.

Specifically, the end portion can be formed by adjusting a gap betweenan upper cutting blade and a lower cutting blade in a slitter deviceused at the time of cutting the lithographic printing plate precursor,the amount of biting, the blade tip angle, and the like.

For example, FIG. 2 is a cross-sectional view illustrating a cuttingportion of a slitter device. A pair of upper and lower cutting blades 10and 20 are horizontally disposed in the slitter device. The cuttingblades 10 and 20 are respectively formed of a round blade on a circularplate and upper cutting blades 10 a and 10 b are supported by a rotaryshaft 11 and lower cutting blades 20 a and 20 b are supported by arotary shaft 21 respectively on the same axis. The upper cutting blades10 a and 10 b and the lower cutting blades 20 a and 20 b rotate inopposite directions. A lithographic printing plate precursor 30 passesthrough the space between the upper cutting blades 10 a and 10 b and thespace between the lower cutting blades 20 a and 20 b and then cut tohave a predetermined width. An end portion with the shear drop can beformed by adjusting the gap between the upper cutting blade 10 a and thelower cutting blade 20 a and the gap between the upper cutting blade 10b and the lower cutting blade 20 b of the cutting portion of the slitterdevice.

The plate-making of the lithographic printing plate precursor of thepresent invention will be described below. According to a preferredembodiment, the plate-making of the lithographic printing plateprecursor of the present invention includes image exposure and on-pressdevelopment.

[Image Exposure]

The image exposure of the lithographic printing plate precursor can beperformed in conformity with an image exposure operation for a typicallithographic printing plate precursor.

The image exposure is performed by laser exposure through a transparentoriginal picture having a line image, a halftone image, and the like orby laser beam scanning using digital data. The wavelength of a lightsource is preferably in a range of 700 to 1,400 nm. As the light sourcehaving a wavelength of 700 to 1,400 nm, a solid-state laser or asemiconductor laser that radiates infrared rays is preferable. Theoutput of the infrared laser is preferably 100 mW or greater, theexposure time per one pixel is preferably less than 20 microseconds, andthe irradiation energy quantity is preferably in a range of 10 to 300mJ/cm². For the purpose of reducing the exposure time, it is preferableto use a multi-beam laser device. The exposure mechanism may be any ofan internal drum system, an external drum system, and a flat bed system.The image exposure can be performed using a plate setter according to ausual method.

[On-Press Development and Printing]

The on-press development and printing of the lithographic printing plateprecursor can be performed according to a usual method. In other words,when dampening water and printing ink are supplied to the image-exposedlithographic printing plate precursor on a printing press, a printingink receiving portion having a lipophilic surface is formed by the imagerecording layer cured by light exposure in the exposed portion of theimage recording layer. Meanwhile, in an unexposed portion, a non-curedimage recording layer is dissolved or dispersed by supplied dampeningwater and/or printing ink and then removed, a hydrophilic surface isexposed to the portion. As the result, dampening water is exposed andadheres to the hydrophilic surface, the printing ink is impressed on theimage recording layer of the exposed region, and then the printing isstarted.

Here, either of dampening water or printing ink may be initiallysupplied to the surface of the lithographic printing plate precursor,but it is preferable that dampening water is initially supplied theretoby infiltrating dampening water so that the on-press developability ispromoted.

In the plate-making of the lithographic printing plate precursoraccording to the present invention, a plate-making system used for atreatment using a typical developer can be employed. That is, aplate-making system including an exposed portion which performs imageexposure on the lithographic printing plate precursor using an exposuremachine; a developing treatment unit which removes an unexposed portionof the lithographic printing plate precursor image-exposed by theexposed portion using an automatic developing machine; and a processingunit which performs processing using a punch vender for mounting thelithographic printing plate precursor on the printing press, in thisorder, can be used.

In a case of on-press development, since the development processing unitis not necessary, the plate-making may be carried out using a systemfrom which the development treatment unit is excluded or may be carriedout while the development treatment unit remains. In a case where theplate-making is performed while the development treatment unit remains,the plate-making is carried out without preparing a developer, water,and a gum solution used in a developing unit, a water washing unit, anda finisher unit of the development treatment unit so that thedevelopment treatment unit can be used as a conveying unit from theexposed portion to the processing unit.

Further, the development treatment unit can be used as the conveyingdevice from the exposed portion to the processing unit by connecting aninsertion roller portion and a plate discharge roller portion of thedevelopment treatment unit using the conveying device such that thesurface of the lithographic printing plate to be conveyed such as a beltconveyor on the photosensitive layer side can be conveyed without cominginto contact with any portion in a conveyance path and skipping thedeveloping unit, the water washing unit, and the finisher unit.

In addition, a development treatment unit having a conveyance pathseparated from the path that conveys the lithographic printing plateprecursor to the developing unit, the water washing unit, and thefinisher unit described in JP2006-65169A can be used.

The lithographic printing plate precursor has an excellentcharacteristic of furnishing a lithographic printing plate in whichadhesion to interleaving paper is prevented, contamination inside adevice is prevented, and edge stain does not occur. This characteristicis remarkable in an on-press development type lithographic printingplate precursor. Particularly, in a case where printing paper having alarger width than the width of the lithographic printing plate precursoris used, as newspaper printing, and printing is carried out, thelithographic printing plate precursor of the present invention exhibitsthe excellent characteristic. In this case, the width of thelithographic printing plate precursor corresponds to the length of thelithographic printing plate precursor in the lateral direction at thetime of being attached to the plate cylinder of the printing press.

Therefore, the lithographic printing plate precursor of the presentinvention exhibits particularly excellent characteristics as an on-pressdevelopment type lithographic printing plate precursor used for printingnewspaper.

EXAMPLES

Hereinafter, the present invention will be described in detail withreference to examples, but the present invention is not limited thereto.Further, in a polymer compound, the molecular weight indicates theweight-average molecular mass (Mw) and the proportion of repeating unitsindicates mole percentage unless otherwise specified.

Examples 1 to 32 and Comparative Examples 1 to 12

[Preparation of Lithographic Printing Plate Precursor 1]

<Preparation of Support>

An aluminum alloy plate having a thickness of 0.3 mm and having acomposition listed in Table A was subjected to the following treatments(a) to (m), whereby a support was produced. Moreover, during alltreatment steps, a washing treatment was performed, and liquid cuttingwas performed using a nip roller after the washing treatment.

TABLE A Composition (% by mass) Si Fe Cu Mn Mg Zn Ti Al 0.085 0.303 10.037 0 0 0 0.018 Remainder

(a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of an aluminum plate as a polishing slurry liquid, with adevice illustrated in FIG. 3, a mechanical roughening treatment wasperformed using rotating bundle bristle brushes. In FIG. 3, thereference numeral 41 is an aluminum plate, the reference numerals 42 and44 are roller-shaped brushes (in the present example, bundle bristlebushes), the reference numeral 43 is a polishing slurry liquid, and thereference numerals 45, 46, 47, and 48 are support rollers.

The mechanical roughening treatment is performed under conditions inwhich the median diameter of a polishing material pumice was 30 μm, thenumber of the bundle bristle brushes was four, and the rotation speed ofthe bundle bristle brushes was set to 250 rpm. The material of thebundle bristle brushes was nylon 6.10, the diameter of the brushbristles was 0.3 mm, and the bristle length was 50 mm. The bundlebristle brushes were produced by implanting bristles densely into theholes in a stainless steel cylinder having a diameter of ϕ300 mm. Thedistance between two support rollers (ϕ200 mm) of the lower portion ofthe bundle bristle brush was 300 mm. The bundle bristle brushes werepressed until the load of a driving motor for rotating the brushesbecame 10 kW plus with respect to the load before the bundle bristlebrushes were pressed against the aluminum plate. The rotation directionof the bundle bristle brushes was the same as the moving direction ofthe aluminum plate.

(b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray tube at a temperature of 70° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was 10g/m².

(c) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a nitric acid aqueoussolution. As the nitric acid aqueous solution used in the desmuttingtreatment, a nitric acid electrolyte used in electrochemical rougheningof the subsequent step was used. The temperature was 35° C. Thedesmutting treatment was performed for 3 seconds by spraying thedesmutting liquid using a spray.

(d) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An electrolyte which had been adjusted to have aconcentration of aluminum ions of 4.5 g/L by adding aluminum nitrate toa nitric acid aqueous solution having a concentration of 10.4 g/L at atemperature of 35° C. was used. Using a trapezoidal rectangular waveformAC having a time tp, until the current value reached a peak from zero,of 0.8 msec and the duty ratio of 1:1 as the AC power supply waveform,the electrochemical roughening treatment was performed using a carbonelectrode as a counter electrode. As an auxiliary anode, ferrite wasused. As an electrolytic cell, the electrolytic cell illustrated in FIG.4 was used. In FIG. 4, an aluminum plate W was wound around a radialdrum roller 52 disposed in a state of being immersed in a mainelectrolytic cell 50 and subjected to an electrolytic treatment by mainpoles 53 a and 53 b connected to an AC power supply 51 in the step ofconveyance. The electrolyte 55 was supplied to an electrolyte passage 57between the radial drum roller 52 and the main poles 53 a and 53 bthrough a slit 56 from an electrolyte supply port 54. The aluminum plateW treated by the main electrolytic cell 50 was subjected to anelectrolytic treatment by an auxiliary anode vessel 60. An auxiliaryanode 58 were disposed to face the aluminum plate W in the auxiliaryanode vessel 60 and the electrolyte 55 was supplied so as to flow thespace between the auxiliary anode 58 and the aluminum plate W. Thecurrent density was 30 A/dm² as the peak current value, and 5% of thecurrent from the power source was separately flowed to the auxiliaryanode. The electric quantity was 185 C/dm² as the sum total of electricquantity at the time of anodization of the aluminum plate. Thereafter,washing with water by spraying was performed.

(e) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray tube at a temperature of 50° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was0.5 g/m².

(f) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a sulfuric acid aqueoussolution. As the sulfuric acid aqueous solution used in the desmuttingtreatment, a solution in which the concentration of sulfuric acid was170 g/L and the concentration of aluminum ions was 5 g/L was used. Thetemperature was 60° C. The desmutting treatment was performed for 3seconds by spraying the desmutting liquid using a spray.

(g) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of hydrochloric acid electrolysis 60 Hz. An electrolytewhich had been adjusted to have a concentration of aluminum ions of 4.5g/L by adding aluminum chloride to an aqueous solution having aconcentration hydrochloric acid of 6.2 g/L at a liquid temperature of35° C. was used. Using a trapezoidal rectangular waveform AC having atime tp, until the current value reached a peak from zero, of 0.8 msecand the duty ratio of 1:1, the electrochemical roughening treatment wasperformed using a carbon electrode as a counter electrode. As anauxiliary anode, ferrite was used. As an electrolytic cell, theelectrolytic cell illustrated in FIG. 4 was used. The current densitywas 25 A/dm² as the peak current value, and the electric quantity in thehydrochloric acid electrolysis was 63 C/dm² as the sum total of electricquantity at the time of anodization of the aluminum plate. Thereafter,washing with water by spraying was performed.

(h) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray tube at a temperature of 50° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was0.1 g/m².

(i) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a sulfuric acid aqueoussolution. The desmutting treatment was performed at a solutiontemperature of 35° C. for 4 seconds using the sulfuric acid aqueoussolution (aluminum ions having a concentration of 5 g/L were containedin a sulfuric acid aqueous solution having a concentration of 170 g/L)used for the anodizing treatment step. The desmutting treatment wasperformed for 3 seconds by spraying the desmutting liquid using a spray.

(j) First Anodizing Treatment

A first step of an anodizing treatment was performed with an anodizingdevice using DC electrolysis having a structure illustrated in FIG. 5.An anodized film having a predetermined film thickness was formed byperforming an anodizing treatment under conditions listed in Table B. Anaqueous solution containing components listed in Table B was used as theelectrolyte. In Tables B to D, the “component concentration” indicatesthe concentration (g/L) of each component described in the section of“liquid component”.

TABLE B First anodizing treatment Component Temper- Current Film LiquidLiquid concentration ature density Time thickness type component (g/L)(° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 55 90 0.40 110 acid

In an anodizing treatment device 610 illustrated in FIG. 5, an aluminumplate 616 was conveyed as indicated by arrows in FIG. 5. The aluminumplate 616 in a power supply vessel 612 in which an electrolyte 618 wasstored was positively (+) charged by a power supply electrode 620.Further, the aluminum plate 616 was conveyed upward by a roller 622 inthe power supply vessel 612, the conveyance direction of the aluminumplate 616 was converted downward by a nip roller 624, the aluminum plate616 was conveyed toward an electrolytic treatment vessel 614 in whichthe electrolyte 626 was stored, and then the conveyance directionthereof was converted into the horizontal direction by a roller 628.Next, when the aluminum plate 616 was negatively (−) charged by anelectrolytic electrode 630, an anodizing film was formed on the surfacethereof and the aluminum plate 616 taken out of the electrolytictreatment vessel 614 was conveyed to the subsequent step. In theanodizing treatment device 610, direction conversion means was formed ofthe roller 622, the nip roller 624, and the roller 628, and the aluminumplate 616 was conveyed to a mountain type and an inverted U type by theabove-described rollers 622, 624, and 628 in a portion between the powersupply vessel 612 and the electrolytic treatment vessel 614. The powersupply electrode 620 and the electrolytic electrode 630 were connectedto a DC power supply 634.

(k) Second Anodizing Treatment

A second step of an anodizing treatment was performed with an anodizingdevice using DC electrolysis having a structure illustrated in FIG. 5.An anodized film having a predetermined film thickness was formed byperforming an anodizing treatment under conditions listed in Table C. Anaqueous solution containing components listed in Table C was used as theelectrolyte.

TABLE C Second anodizing treatment Component Temper- Current Film LiquidLiquid concentration ature density Time thickness type component (g/L)(° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 15 13 900 acid

(l) Third Anodizing Treatment

A third step of an anodizing treatment was performed with an anodizingdevice using DC electrolysis having a structure illustrated in FIG. 5.An anodized film having a predetermined film thickness was formed byperforming an anodizing treatment under conditions listed in Table D. Anaqueous solution containing components listed in Table D was used as theelectrolyte.

TABLE D Third anodizing treatment Component Temper- Current Film LiquidLiquid concentration ature density Time thickness type component (g/L)(° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 50 0.4 100 acid

(m) Hydrophilization Treatment

In order to ensure hydrophilicity of a non-image portion, the non-imageportion was subjected to a silicate treatment by being dipped using0.2.5% by mass of a No. 3 sodium silicate aqueous solution at 50° C. for7 seconds. The adhesion amount of Si was 8.5 mg/m². Thereafter, theresultant was washed with water using a spray.

The average diameter (average diameter of surface layer) of alarge-diameter hole portion on the surface of the anodized film havingmicropores obtained in the above-described manner, the average diameter(average diameter of bottom portion) of the large-diameter hole portionin a communication position, the average diameter (diameter ofsmall-diameter hole portion) of a small-diameter hole portion in thecommunication position, the average depth of the large-diameter holeportion and the small-diameter hole portion, the thickness (thickness ofbarrier layer) of the anodized film from the bottom portion of thesmall-diameter hole portion to the surface of the aluminum plate, andthe density of the small-diameter hole portion are listed in Table E.The small-diameter hole portion includes a first small-diameter holdportion and a second small-diameter hole portion with depths differentfrom each other and a small-diameter hole portion which is deeper thanthe other is referred to as the first small-diameter hole portion.

TABLE E (part 1) Micropore Large-diameter hole portion Average AverageAverage Average diameter of diameter of Average depth/averagedepth/average surface layer bottom depth diameter of diameter of (nm)portion (nm) (nm) surface layer bottom portion Shape 12 25 98 8.2 3.9Inverted taper (part 2) Micropore Small-diameter hole portion Ratio(average Average Minimum diameter of Density of thickness thicknesssurface layer/ Average Average communication of barrier of barrierDensity of Increase diameter of diameter depth portion layer layermicropores magnification small-diameter (nm) (nm) (portions/μm²) (nm)(nm) (pores/μm²) of surface area hole portion) 9.8 888, 800 17 16 5004.0 1.22 968  (650)

In Table E, the average value and the minimum value are shown as thebarrier layer thickness. The average value is obtained by measuring 50thicknesses of the anodized film from the bottom portion of the firstsmall-diameter hole portion to the surface of the aluminum plate andarithmetically averaging the values.

The average diameter of micropores (average diameter of thelarge-diameter hole portion and the small-diameter hole portion) is avalue obtained by observing 4 sheets (N=4) of the surfaces of thelarge-diameter hole portion and the surfaces of the small-diameter holeportion using FE-SEM at a magnification of 150,000, measuring thediameters of micropores (the large-diameter hole portion and thesmall-diameter hole portion) present in a range of 400×600 nm² in theobtained four sheets of images, and averaging the values. Further, in acase where the depth of the large-diameter hole portion is deep and thediameter of the small-diameter hole portion is unlikely to be measured,the upper portion of the anodized film is cut and then various kinds ofdiameters are acquired.

The average depth of the large-diameter hole portion is a value obtainedby measuring the cross section of the support (anodized film) usingFE-TEM at a magnification of 500,000, measuring 60 cases (N=60) ofdistances from the surface of an arbitrary micropore to thecommunication position in the obtained image, and averaging the values.Further, the average depth of the small-diameter hole portion is a valueobtained by observing the cross section of the support (anodized film)using FE-SEM (at a magnification of 50,000), measuring 25 cases ofdepths of arbitrary micropores in the obtained image, and averaging thevalues.

The “density of the communication portion” indicates the density of thesmall-diameter hole portion of the cross section of the anodized film inthe communication position. The “increase magnification of the surfacearea” indicates the value calculated based on the following Equation(A).

Increase magnification of surface area=1+pore density×((π×(averagediameter of surface layer/2+average diameter of bottomportion/2)×((average diameter of bottom portion/2−average diameter ofsurface layer/2)²+depth A ²)^(1/2)+π×(average diameter of bottomportion/2)²−π×(average diameter of surface layer/2)²))  Equation (A)

In the column of the “average depth (nm)” of the small-diameter holeportion, the average depth of the second small-diameter hole portion isshown on the left side and the average depth of the first small-diameterhole portion is shown on the right side. In the column of the “densityof communication portion” of the small-diameter hole portion in Table E,the density of the first small-diameter hole portion is shown in theparentheses together with the density of the communication portion ofthe small-diameter hole portion.

In addition, the average diameter of the first small-diameter holeportion positioning from the bottom portion of the second small-diameterhole portion to the bottom portion of the first small-diameter holeportion was approximately 12 nm.

<Formation of Undercoat Layer>

The support was coated with an undercoat layer coating solution (1) withthe following composition such that the drying coating amount was set to20 mg/m², thereby forming an undercoat layer.

(Undercoat layer coating solution (1)) Compound (1) for undercoat layer(the following structure) 0.18 g Hydroxyethyl imino diacetic acid 0.05 gSurfactant (EMALEX 710, manufactured by Nihon Emulsion 0.03 g Co., Ltd.)Preservative (BIOHOPE, manufactured by K•I CHEMICAL 0.01 g INDUSTRY CO.,LTD.) Water 28.0 g

<Formation of Image Recording Layer>

The undercoat layer was bar-coated with an image recording layer coatingsolution (1) with the following composition and dried in an oven at 100°for 60 seconds, thereby forming an image recording layer having a dryingcoating amount of 1.0 g/m².

The image recording layer coating solution (1) was obtained by mixing aphotosensitive solution (1) and a microgel solution (1) described belowimmediately before the coating and then stirring the solution.

(Image recording layer coating solution (1)) (Photosensitive solution(1)) Binder polymer (1) (the following structure) 0.240 g (Mw: 55,000and n: 2 (number of EO units)) Infrared absorbing agent (1) (thefollowing structure) 0.020 g Borate compound (1) 0.010 g Sodiumtetraphenyl borate Polymerization initiator (1) (the followingstructure) 0.162 g Polymerizable compound 0.192 g Tris(acryloyloxyethyl) isocyanurate (NK ESTER A-9300, manufactured byShin-Nakamura Chemical Co., Ltd.) Anionic surfactant 1 (the followingstructure) 0.050 g Oil sensitizing agent 0.055 g Phosphonium compound(1) (the following structure) Oil sensitizing agent 0.018 g Benzyldimethyl octyl ammonium · PF₆ salt Oil sensitizing agent 0.040 gAmmonium group-containing polymer (the following structure) (Mw: 50,000,reduction specific viscosity: 45 ml/g) Fluorine-based surfactant (1)(the following structure) 0.008 g 2-butanone 1.091 g1-methoxy-2-propanol 8.609 g (Microgel solution (1)) Microgel (1) 2.640g Distilled water 2.425 g

(Preparation of Microgel (1))

As oil phase components, 10 g of an adduct (50% by mass of ethyl acetatesolution, manufactured by Mitsui Chemical, Inc.) formed by adding 4.46 gof polyfunctional isocyante (75 mass % ethyl acetate solution,manufactured by Mitsui Chemical, Inc.) having the following structure,trimethylolpropane (6 mol), and xylene diisocyanate (18 mol), and addingmethyl one-terminal polyoxyethylene (1 mol, repetition number ofoxyethylene units: 90), 3.15 g of pentaerythritol triacrylate (SR444,manufactured by Nippon Kayaku Co., Ltd.), and 0.1 g of an anionicsurfactant (PIONINE A-41C, manufactured by TAKEMOTO OIL & FAT Co., Ltd.)were dissolved in 17 g of ethyl acetate. As water phase components, 40 gof a 4 mass % aqueous solution of polyvinyl alcohol (PVA-205,manufactured by KURARAY CO., LTD.) was prepared. The oil phasecomponents and the water phase components were mixed with each other andemulsified at 12,000 rpm for 10 minutes using a homogenizer. 25 g ofdistilled water was added to the obtained emulsion, and the resultantwas stirred at room temperature for 30 minutes and stirred at 50° C. for3 hours. The microgel solution obtained in this manner was diluted withdistilled water such that the concentration of solid contents was set to15% by mass, thereby preparing a microgel (1). The average particlediameter of the microgel measured by a light scattering method was 0.2μm.

<Formation of Protective Layer>

The image recording layer was bar-coated with a protective layer coatingsolution (1) with the following composition and dried in an oven at 120°for 60 seconds to form a protective layer having a drying coating amountof 0.15 g/m², thereby preparing a lithographic printing plate precursor1.

(Protective layer coating solution (1)) Inorganic layered compounddispersion liquid (1) (described below) 1.5 g Hydrophilic polymer (1)(the following structure, Mw: 30,000) (solid content) 0.03 g Polyvinylalcohol (CKS50, manufactured by Nippon Synthetic Chemical Industry 0.10g Co., Ltd., sulfonic acid-modified, saponification degree: 99% by moleor greater, degree of polymerization: 300) 6 mass % aqueous solutionPolyvinyl alcohol (PVA-405, manufactured by KURARAY CO., LTD., 0.03 gsaponification degree: 81.5% by mole, degree of polymerization: 500), 6mass % aqueous solution Surfactant (EMALEX 710, manufactured by NihonEmulsion Co., Ltd.) 0.86 g (the following structure) 1 mass % aqueoussolution Ion exchange water 6.0 g

C₁₂H₂₅—(OCHCH₂)₁₀—OH EMALEX 710

(Preparation of Inorganic Layered Compound Dispersion Liquid (1))

6.4 g of synthetic mica Somasif ME-100 (manufactured by CO-OP CHEMICALCO., LTD.) was added to 193.6 g of ion exchange water and dispersed suchthat the volume average particle diameter (laser scattering method) wasset to 3 μm using a homogenizer. The aspect ratio of the obtaineddispersed particles was 100 or greater.

[Preparation of Lithographic Printing Plate Precursor 2]

<Formation of Image Recording Layer>

The undercoat layer of the support having the undercoat layer used forpreparation of the lithographic printing plate precursor 1 wasbar-coated with an image recording layer coating solution (2) with thefollowing composition and dried in an oven at 70° for 60 seconds,thereby forming an image recording layer having a drying coating amountof 0.6 g/m².

(Image recording layer coating solution (2)) Thermoplastic polymer fineparticle aqueous dispersion liquid 20.0 g (described below) Infraredabsorbing agent (2) (the following structure)  0.2 g Polymerizationinitiator  0.4 g IRGACURE 250 (manufactured by Ciba Specialty Chemicals,Inc.) Polymerization initiator (2) (the following structure) 0.15 gPolymerizable compound SR-399 (manufactured by Sartomer 1.50 g JapanInc.) Mercapto-3-triazole  0.2 g Byk336 (manufactured by BYK ChemieGmbH)  0.4 g Klucel M (manufactured by Hercules, Inc.)  4.8 g ELVACITE4026 (manufactured by Ineos Acrylics Ltd.)  2.5 g Anionic surfactant 1(the above-described structure) 0.15 g n-propanol 55.0 g 2-butanone 17.0g

The compounds described with the trade names in the composition above asfollows.

-   -   IRGACURE 250:        (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium=hexafluorophosphate        (75 mass % propylene carbonate solution)    -   SR-399: dipentaerythritolpentaacrylate    -   Byk336: modified dimethyl polysiloxane copolymer (25 mass %        xylene/methoxy propyl acetate solution)    -   Klucel M: hydroxypropyl cellulose (2 mass % aqueous solution)    -   ELVACITE 4026: highly branched polymethyl methacrylate (10 mass        % 2-butanone solution)

(Preparation of Thermoplastic Polymer Fine Particle Aqueous DispersionLiquid)

Nitrogen gas was introduced into a 1,000 ml four-necked flask equippedwith a stirrer, a thermometer, a dropping funnel, a nitrogenintroduction pipe, and a reflex condenser, deoxygenation was performed,10 g of polyethylene glycol methyl ether methacrylate (PEGMA, averagenumber of repeating units of ethylene glycol: 20), 200 g of distilledwater, and 200 g of n-propanol were added thereto, and then the mixturewas heated until the internal temperature thereof was set to 70° C.Next, a mixture of 10 g of styrene (St), 80 g of acrylonitrile (AN), and0.8 g of 2,2′-azobisisobutyronitrile prepared in advance was addeddropwise for 1 hour. After dropwise addition was finished, the reactionwas allowed to be continued for 5 hours, 0.4 g of2,2′-azobisisobutyronitrile was added thereto, and the mixture washeated until the internal temperature was set to 80° C. Subsequently,0.5 g of 2,2′-azobisisobutyronitrile was added for 6 hours. The totaldegree of polymerization at the stage of the continued reaction for 20hours was 98% or greater, and a thermoplastic polymer fine particleaqueous dispersion liquid having PEGMA, St, and AN at a mass ratio of10/10/80 was obtained. The particle size distribution of thethermoplastic polymer fine particle has a maximum value at 150 nm of thevolume average particle diameter.

Here, the particle size distribution was acquired by imaging an electronmicrograph of polymer fine particles, measuring the total number of5,000 particle diameters of fine particles on the photograph, dividingthe interval from the maximum value of the obtained measured value ofthe particle diameter to 0 into the logarithmic scale of 50, andplotting the appearance frequency of each particle diameter. Further,the particle diameter of a spherical particle having the same particlearea as the particle area on the photograph was set to the particlediameter, as non-spherical particles.

[Preparation of Lithographic Printing Plate Precursor 3]

<Preparation of Support>

An aluminum plate having a thickness of 0.19 mm was immersed in a 40 g/Lsodium hydroxide aqueous solution at 60° C. for 8 seconds so as to bedegreased and then washed with demineralized water for 2 seconds. Next,the aluminum plate was subjected to an electrochemical rougheningtreatment in an aqueous solution containing 12 g/L of hydrochloric acidand 38 g/L of aluminum sulfate (18 hydrate) at a temperature of 33° C.and at a current density of 130 A/dm² using an AC for 15 seconds. Next,the aluminum plate was washed with demineralized water for 2 seconds,subjected to a desmutting treatment by being etched using 155 g/L of asulfuric acid aqueous solution at 70° C. for 4 seconds, and washed withdemineralized water at 25° C. for 2 seconds. The aluminum plate wassubjected to an anodizing treatment in 155 g/L of a sulfuric acidaqueous solution for 13 seconds at a temperature of 45° C. and at acurrent density of 22 A/dm² and washed with demineralized water for 2seconds. Further, the aluminum plate was treated at 40° C. for 10seconds using 4 g/L of a polyvinyl phosphonic acid aqueous solution,washed with demineralized water at 20° C. for 2 seconds, and then dried,thereby preparing a support. The surface roughness Ra of the support was0.21 m and the amount of the anodized film was 4 g/m².

<Formation of Image Recording Layer>

An image recording layer aqueous coating solution containingthermoplastic polymer fine particles, an infrared absorbing agent, andpolyacrylic acid described below was prepared, the pH thereof wasadjusted to 3.6, and a support was coated with the coating solution anddried at 50° C. for 1 minute to form an image recording layer, therebypreparing a lithographic printing plate precursor 3. The coating amountafter the drying of each component is shown below.

Thermoplastic polymer fine particles: 0.7 g/m²

Infrared absorbing agent IR-01: 1.20×10⁻⁴ g/m²

Polyacrylic acid: 0.09 g/m²

The thermoplastic polymer fine particles, the infrared absorbing agentIR-01, the polyacrylic acid used for the image recording layer coatingsolution are as follows.

Thermoplastic polymer fine particles: styrene-acrylonitrile copolymer(molar ratio of 50:50), Tg: 99° C., volume average particle diameter: 60nm

Infrared absorbing agent IR-01: infrared absorbing agent having thefollowing structure

Polyacrylic acid, Mw: 250,000

[Specific Polymer]

Polymer P-1 (Amino Group-Containing Polyamide)

200 g of a 50% aqueous solution formed of aminoethylpiperazine andadipic acid was reacted in an autoclave at 280° C. to 285° C. for 10hours in a nitrogen atmosphere. The resulting solution was allowed to benaturally cooled to room temperature, thereby obtaining an aminogroup-containing polyamide aqueous solution having a concentration of50% (weight average molecular weight: 30000).

Polymer P-2 (Sulfo Group-Containing Polyurethane)

19.5 g of the compound represented by the following Structural Formula1, 20.3 g of isophorone diisocyanate (manufactured by Wako Pure ChemicalIndustries, Ltd.), 65.0 g of N,N-dimethylacetamide, and 5 drops ofdi-n-butyltin dilaurate were put into a 500 mL of three-neck roundbottom flask equipped with a condenser and a stirrer, and the mixturewas heated at 65° C. for 8 hours. Thereafter, the solution was dilutedwith 100 mL of methanol and 200 mL of N,N-dimethylacetamide. Thereaction solution was poured into 4 L of ethyl acetate while stirring,and a white polymer was precipitated. This polymer was separated byfiltration, washed with ethyl acetate, and dried in a vacuum, therebyobtaining sulfo group-containing polyurethane (weight average molecularweight: 95000).

Polymer P-3 (Sulfo Group and Phosphoric Acid Group-ContainingPolyurethane)

18.4 g of the compound represented by Structural Formula 1, 0.71 g ofthe compound represented by the following Structural Formula 2, 20.3 gof isophorone diisocyanate (manufactured by Wako Pure ChemicalIndustries, Ltd.), 65.0 g of N,N-dimethylacetamide, and 5 drops ofdi-n-butyltin dilaurate were put into a 500 mL of three-neck roundbottom flask equipped with a condenser and a stirrer, and the mixturewas heated at 65° C. for 8 hours. Thereafter, the solution was dilutedwith 100 mL of methanol and 200 mL of N,N-dimethylacetamide. Thereaction solution was poured into 4 L of ethyl acetate while stirring,and a white polymer was precipitated. This polymer was separated byfiltration, washed with ethyl acetate, and dried in a vacuum, therebyobtaining phosphoric acid group-containing polyurethane (weight averagemolecular weight: 50000).

Polymer P-4 (Carboxy Group-Containing Polyurea)

Carboxy group-containing polyurea synthesized according to thedescription of Example 1 in JP1995-82333A (JP-H07-82333A) (weightaverage molecular weight: 50000).

Polymer P-5 (Sulfo Group-Containing Polyester)

Plus Coat Z-561 (manufactured by GOO CHEMICAL CO., LTD.).

Polymer P-6 (Carboxy Group-Containing Polycarbonate)

Carboxy group-containing polycarbonate described in Comparative Example5 of WO2012/165569A

Polymer P-7 (Polyamide)

N-methoxymethylated nylon (Torezine F-30K, manufactured by NagaseChemteX Corporation)

<Preparation of Specific Polymer-Containing Coating Solution>

The components described in the following Table F were added to purewater and stirred, thereby preparing a polymer-containing coatingsolution. The polymer P-7 was prepared by adding the methanol solution(20%) to pure water. Further, the “coating solution a” to “coatingsolution b” are coating solutions for comparison and contain polyacrylicacid in place of the specific polymer.

Specific polymer-containing Specific polymer coating solution (% bymass) Additive (% by mass) A Polymer P-1 (1.5) — B Polymer P-2 (1.5) — CPolymer P-3 (1.5) — D Polymer P-4 (1.5) — E Polymer P-5 (1.5) — FPolymer P-6 (1.5) — G Polymer P-2 (1.5) Sodium dihydrogen phosphate(0.1) H Polymer P4 (1.5) Sodium dihydrogen phosphate (0.1) I PolymerP-5(1.5) Sodium dihydrogen phosphate (0.1) J Polymer P-7 (1.5) K PolymerP-7 (1.5) Sodium dihydrogen phosphate (0.1) a Polyacrylic — acid *¹⁾(1.5) b Polyacrylic Sodium dihydrogen acid *¹⁾ (1.5) phosphate (0.1) *¹⁾Weight average molecular weight: 25000

<Applying and Cutting of Specific Polymer-Containing Coating Solution>

After the specific polymer-containing coating solution was applied,cutting was performed according to the following method.

The specific polymer-containing coating solution was applied such thatthe solid content coating amount was set to a predetermined value byadjusting the conveying speed using 2NL04 (manufactured by HEISHIN Ltd.)as a coating device according to a dispenser method at a clearance of0.3 mm and at a feed amount of 5 ml/min.

The fine particle-containing coating solution was applied to a region ata width of 10 mm from two sides of both end portions facing thelithographic printing plate precursor to positions respectivelyseparated by a distance of 3 cm.

<Time of Applying Specific Polymer-Containing Coating Solution>

The time of applying the specific polymer-containing coating solution isas described in the following (1) to (5).

(1) A support was coated with the specific polymer-containing coatingsolution and then dried at 85° C. for 30 seconds.

(2) The support was coated with an undercoat layer, coated with thespecific polymer-containing coating solution without drying, and thendried at 80° C. for 30 seconds.

(3) The support was coated with an undercoat layer, coated with thespecific polymer-containing coating solution without drying, and thendried at 150° C. for 20 seconds.

(4) The support was coated with a protective layer (after the supportwas coated with an image recording layer in a case where the formationof a protective layer was not carried out), coated with the specificpolymer-containing coating solution without drying, and then dried at150° C. for 1 minute.

(5) The support was coated with a protective layer (after the supportwas coated with an image recording layer in a case where the formationof a protective layer was not carried out) and coated with the specificpolymer-containing coating solution after the support was dried at 120°C. for 1 minute. Thereafter, the support was dried at 120° C. for 1minute.

The lithographic printing plate precursor was coated with the specificpolymer-containing coating solution by combining the specificpolymer-containing coating solution, the lithographic printing plateprecursor, and the time of coating the lithographic printing plateprecursor with the coating solution as listed in Table G

<Cutting>

The lithographic printing plate precursor was cut to have a shape of anend portion with a desired amount of shear drop and a desired width ofshear drop by adjusting a gap between an upper cutting blade and a lowercutting blade, the amount of biting, and the blade tip angle using arotary blade as illustrated in FIG. 2. The central position of a regioncoated with the specific polymer-containing coating solution was set toa cutting position under the above-described cutting conditions and twoplaces of the lithographic printing plate precursor was cut. When theshear drop shape was measured by the following method, the amount ofshear drop was 60 μm and the width of shear drop was 150 μm.

<Cutting and then Applying Specific Polymer-Containing Coating Solution>

After the lithographic printing plate precursor was cut, the specificpolymer-containing coating solution was applied according to thefollowing method.

<Cutting>

The lithographic printing plate precursor was continuously cut to have ashape of an end portion with a desired amount of shear drop and adesired width of shear drop by adjusting a gap between an upper cuttingblade and a lower cutting blade, the amount of biting, and the blade tipangle using a rotary blade as illustrated in FIG. 2. When the shear dropshape was measured by the following method, the amount of shear drop was60 μm and the width of shear drop was 150 μm.

The shear drop shape was measured using a surface roughness meter(SURFCOM, manufactured by TOKYO SEMITSU CO., LTD.). The model number480A was used as the surface roughness meter and a stylus having adiameter of 2 μm was used. The shear drop shape was measured by movingthe stylus toward an end portion of the lithographic printing plateprecursor from the inside by a distance of approximately 1 mm at a speedof 3 mm/sec.

<Method of Applying Specific Polymer-Containing Coating Solution>

The method of applying the specific polymer-containing coating solutionis as described in the following (1) to (4).

(1) Aero Jet (manufactured by Musashi Engineering Inc.) having anon-contact dispenser system was used as a coating device. The conveyingspeed was adjusted so as to have a desired coating amount under theconditions of a clearance of 6 mm and a discharge pressure of 0.05 MPa,the specific polymer-containing coating solution was applied to a regionfrom the end portion of the lithographic printing plate precursor to aportion inside the end portion by 5 mm, and then the lithographicprinting plate precursor was dried at 120° C. for 1 minute using aconstant-temperature tank PH-201 (manufactured by ESPEC CORP.).

(2) Cloth containing the specific polymer-containing coating solutionwas brought into contact with the end portions of the lithographicprinting plate precursor, the specific polymer-containing coatingsolution was applied to a region from the end portion of thelithographic printing plate precursor to a portion inside the endportion by 5 mm while the cloth was allowed to slide along the endportions, and then the lithographic printing plate precursor was driedat 120° C. for 1 minute using a constant-temperature tank PH-201(manufactured by ESPEC CORP.).

(3) Cloth containing the specific polymer-containing coating solutionwas brought into contact with the end portions of the lithographicprinting plate precursor, the specific polymer-containing coatingsolution was applied to a region from the end portion of thelithographic printing plate precursor to a portion inside the endportion by 5 mm by pressing the cloth from the top, and then thelithographic printing plate precursor was dried at 120° C. for 1 minuteusing a constant-temperature tank PH-201 (manufactured by ESPEC CORP.).

(4) A brush containing the specific polymer-containing coating solutionwas brought into contact with the end portions of the lithographicprinting plate precursor, the specific polymer-containing coatingsolution was applied to a region from the end portion of thelithographic printing plate precursor to a portion inside the endportion by 5 mm, and then the lithographic printing plate precursor wasdried at 120° C. for 1 minute using a constant-temperature tank PH-201(manufactured by ESPEC CORP.).

The lithographic printing plate precursor was coated with the specificpolymer-containing coating solution by combining the specificpolymer-containing coating solution, the lithographic printing plateprecursor, and the application of the specific polymer-containingcoating solution as listed in Table G.

<Plate-Making of Lithographic Printing Plate Precursor>

The lithographic printing plate precursor prepared in theabove-described manner was exposed in Luxel PLATESETTER T-6000III(manufactured by Fujifilm Corporation) equipped with an infraredsemiconductor laser under conditions of external surface drum rotationspeed of 1,000 rpm, a laser output of 70%, and a resolution of 2,400dpi. The exposed image had a solid image and a 50% halftone dot chart.

[Evaluation of Lithographic Printing Plate Precursor]

<Evaluation of Performance of Preventing Edge Stain>

The lithographic printing plate precursor after image exposure wasmounted on an offset rotary press (manufactured by Touhin Seiki K.K),and printing was performed on newsprint paper at a speed of 100,000sheets/hour under standard water graduation conditions using SOIBIKKST-S(red) (manufactured by Dai Nippon Printing Co., Ltd.) as printingink for newspaper and TOYO ALKY (manufactured by TOYO INK CO., LTD.) asdampening water. In the above-described printing step, 1,000-th printedmatter was sampled, the degree of linear stain on an edge portion wasvisually observed, and then the evaluation was performed based on thefollowing standard. The value of 5 to 3 is an acceptable level.

The results are listed in Table G.

5: Stain was not observed at all.

4: An intermediate level between 5 and 3.

3: A slight amount of stain was observed.

2: An intermediate level between 3 and 1.

1: Stain was clearly observed.

<Evaluation of Adhesion Between Interleaving Paper and LithographicPrinting Plate Precursor>

The prepared lithographic printing plate precursor and interleavingpaper were humidity-controlled for 1 hour under the conditions of atemperature of 25° C. and a relative humidity of 50% RH. When a state inwhich one sheet of humidity-controlled interleaving paper was placed onone sheet of humidity-controlled lithographic printing plate precursorwas set to one set, 50 sets were stored at 25° C. for 3 day in a statein which the sets were stacked on each other and 20 (kg/cm²) of pressurewas applied to the plate surface using a vise. Thereafter, the peelingproperties of the interleaving paper in contact with the end portionregion of the lithographic printing plate precursor were evaluated basedon the following standard. The value of 5 to 3 is an acceptable level.The results are listed in Table G.

5: Adhesion between the interleaving paper and the end portion region ofthe lithographic printing plate precursor was not recognized at all andthe interleaving paper was easily peeled off.

4: The interleaving paper was slightly adhered to the end portion regionof the lithographic printing plate precursor, but the interleaving paperdid not have transferred matter when peeled off.

3: The interleaving paper was slightly adhered to the end portion regionof the lithographic printing plate precursor, and the interleaving paperhad a slight amount of transferred matter when peeled off.

2: The interleaving paper was adhered to the end portion region of thelithographic printing plate precursor, and transferred matter in a shapeof a, continuous line was found on the interleaving paper when theinterleaving paper was peeled off.

1: The interleaving paper was adhered to the end portion region of thelithographic printing plate precursor, and transferred matter in a shapeof a continuous line was clearly found on the interleaving paper whenthe interleaving paper was peeled off.

The interleaving paper was prepared by beating bleached kraft pulp andadding 0.4% by mass of a neutral size agent of alkyl ketene dimer (AKD)and 5.0% by mass of calcium carbonate to paper stock diluted to aconcentration of 4% by mass. 3.0% by mass of a paper strengthening agentcontaining starch as a main component was applied to the paper stock sothat paper-making was carried out, the resulting paper was nipped at alinear pressure of 18 kg/cm using a resin roll with a 2-nip softcalendar, and calendaring was performed, thereby preparing interleavingpaper 1 having a basis weight 48 g/m² and a moisture content of 5.5% bymass.

In the following Table G, the “difference between contents of thespecific polymer” indicates a difference between the content of thespecific polymer per unit area in the end portion region of thelithographic printing plate precursor and the content of the specificpolymer per unit area in a region other than the above-described region.In Comparative Examples 1 to 3, since the specific polymer was notapplied to the end portion regions of the lithographic printing plateprecursors, the “difference between contents of the specific polymer”were not measured. In Comparative Examples 5 to 12, the “differencebetween contents of the specific polymer” indicates a difference betweencontents of polyacrylic acid. The “time of coating” indicates the timeof coating the positions corresponding to the end portion regions of thelithographic printing plate precursor with the specificpolymer-containing coating solution during the step of formingconfiguration layers of the lithographic printing plate precursor. The“coating method” indicates the method of coating the end portion regionsof the lithographic printing plate precursor with the specificpolymer-containing coating solution after the lithographic printingplate precursor produced by performing the step of forming configurationlayers of the lithographic printing plate precursor was cut.

TABLE G Difference Specific between polymer- contents Lithographiccontaining of specific Adhesion to printing plate coating polymer Timeof Coating Edge interleaving precursor solution (mg/m²) coating methodstain paper (part 1) Example 1 1 A 505 2 — 4 5 Example 2 1 B 503 2 — 4 5Example 3 1 C 502 2 — 4 5 Example 4 1 D 507 2 — 4 5 Example 5 1 E 504 2— 4 5 Example 6 1 F 502 2 — 4 5 Example 7 1 G 510 2 — 5 5 Example 8 1 H513 2 — 5 4 Example 9 1 I 513 2 — 5 4 Example 10 1 B 895 2 — 5 4 Example11 1 B 100 2 — 4 5 Example 12 1 B 53 2 — 4 5 Example 13 1 B 12 2 — 3 5Example 14 1 G 910 2 — 5 4 Example 15 1 J 511 2 — 3 5 Example 16 1 K 5082 — 3 5 Example 17 2 B 500 2 — 4 5 Example 18 2 G 503 2 — 5 4 Example 193 B 505 1 — 4 5 Example 20 3 G 508 1 — 5 4 Example 21 1 G 447 1 — 5 4Example 22 1 G 512 3 — 5 4 Example 23 1 G 1524 4 — 5 3 Example 24 1 G1533 5 — 5 3 Example 25 1 G 520 — 1 5 4 Example 26 1 H 511 — 1 5 4Example 27 1 I 513 — 1 5 4 Example 28 1 J 522 — 1 5 3 Example 29 1 K 508— 1 5 3 Example 30 1 G 3540 — 2 5 3 Example 31 1 G 4130 — 3 5 3 Example32 1 G 4988 — 4 5 3 (part 2) Comparative 1 — — — 1 1 5 Example 1Comparative 2 — — — — 1 5 Example 2 Comparative 3 — — — — 1 5 Example 3Comparative 1 G 5 2 — 2 5 Example 4 Comparative 1 a 503 2 — 3 2 Example5 Comparative 1 b 507 2 — 4 1 Example 6 Comparative 2 a 510 2 — 3 2Example 7 Comparative 3 a 505 1 — 3 2 Example 8 Comparative 1 b 499 — 13 1 Example 9 Comparative 1 b 3560 — 2 4 1 Example 10 Comparative 1 b4030 — 3 4 1 Example 11 Comparative 1 b 5023 — 4 4 1 Example 12

From the results listed in the above-described Table G in thelithographic printing plate precursor according to the presentinvention, specifically containing a large amount of the specificpolymer, in the end portion regions, it was understood that edge staindoes not occur, adhesion to interleaving paper is prevented even in acase where lithographic printing plate precursor and interleaving paperare stored in a stacked state, and the interleaving paper issatisfactorily peeled off from the lithographic printing plateprecursor. Meanwhile, the lithographic printing plate precursors of thecomparative examples in which the specific polymer is not applied to theend portion regions or the difference between contents is less than 10mg/m² are insufficient in at least one of preventing occurrence of edgestain or preventing adhesion to interleaving paper. Further, inComparative Examples 5 to 12, after 20 sheets of lithographic printingplate precursors were produced, contamination originated from the endportion treatment regions of the lithographic printing plate precursorswere found at positioning pins used to adjust the positions of thelithographic printing plate precursors before the lithographic printingplate precursor were mounted on a drum of an exposure machine, but therewas no contamination found in the lithographic printing plate precursorof the present invention.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to provide alithographic printing plate precursor for furnishing a lithographicprinting plate in which adhesion to interleaving paper is prevented,contamination inside a device is prevented, and edge stain does notoccur; a method of producing the same; and a printing method using thesame.

The present invention has been described with reference to detailed andspecific embodiments, but various changes or modifications can be madewithout departing from the spirit and the scope of the present inventionand this is apparent to those skilled in the art.

The present application is based on Japanese Patent Application(JP2015-015962) filed on Jan. 29, 2015 and the contents of which areincorporated herein by reference.

EXPLANATION OF REFERENCES

-   -   1: lithographic printing plate precursor    -   1 a: image recording layer surface    -   1 b: support surface    -   1 c: end surface    -   2: shear drop    -   X: amount of shear drop    -   Y: width of shear drop    -   B: boundary between image recording layer and support    -   10: cutting blade    -   10 a: upper cutting blade    -   10 b: upper cutting blade    -   11: rotary shaft    -   20: cutting blade    -   20 a: lower cutting blade    -   20 b: lower cutting blade    -   21: rotary shaft    -   30: lithographic printing plate precursor    -   41: aluminum plate    -   42, 44: roller-shaped brush    -   43: polishing slurry liquid    -   45, 46, 47, 48: support roller    -   50: main electrolytic cell    -   51: AC power supply    -   52: radial drum roller    -   53 a, 53 b: main pole    -   54: electrolyte supply port    -   55: electrolyte    -   56: slit    -   58: auxiliary anode    -   60: auxiliary anode vessel    -   W: aluminum plate    -   610: anodizing treatment device    -   612: power supply vessel    -   614: electrolytic treatment vessel    -   616: aluminum plate    -   618, 626: electrolyte    -   620: power supply electrode    -   622, 628: roller    -   624: nip roller    -   630: electrolytic electrode    -   632: vessel wall    -   634: DC power supply

What is claimed is:
 1. A lithographic printing plate precursorcomprising: a support; and an image recording layer on the support,wherein a region of a surface of the lithographic printing plateprecursor at a side of the image recording layer, which is from an endportion of the lithographic printing plate precursor to a portion insidethe end portion by 5 mm, contains at least one polymer selected from: apolymer having an amide bond of the structure —NRC(═O)— in which Rrepresents a hydrogen atom or a substituent in a main chain or a graftchain and derivatives of the polymer; a polymer having a urethane bondof the structure —NRC(═O)O— in which R represents a hydrogen atom or asubstituent in a main chain or a graft chain and derivatives of thepolymer; a polymer having a urea bond of the structure —NRC(═O)NR— inwhich R represents a hydrogen atom or a substituent in a main chain or agraft chain and derivatives of the polymer; a polymer having an esterbond of the structure —C(═O)O— in a main chain or a graft chain andderivatives of the polymer; and a polymer having a carbonate bond of thestructure —OCOO— in a main chain or a graft chain and derivatives of thepolymer, and has a content of the polymer per unit area which is greaterthan a content of the polymer per unit area in a region other than theregion of a surface of the lithographic printing plate precursor at aside of the image recording layer by an amount of 10 mg/m² or greater,and wherein the end portion of the lithographic printing plate precursorhas a shear drop shape.
 2. The lithographic printing plate precursoraccording to claim 1, wherein the end portion of the lithographicprinting plate precursor has a shear drop shape in which an amount ofthe shear drop is in a range of 35 to 150 μm.
 3. The lithographicprinting plate precursor according to claim 1, wherein the polymer has aweight average molecular weight of from 2,000 to 1,000,000.
 4. Thelithographic printing plate precursor according to claim 1, wherein theregion of a surface of the lithographic printing plate precursor at aside of the image recording layer, which is from an end portion of thelithographic printing plate precursor to a portion inside the endportion by 5 mm, further contains a hydrophilic compound.
 5. Thelithographic printing plate precursor according to claim 4, wherein thehydrophilic compound is a phosphoric acid compound or a phosphonic acidcompound.
 6. The lithographic printing plate precursor according toclaim 1, wherein the image recording layer contains a borate compound.7. The lithographic printing plate precursor according to claim 1,wherein the image recording layer contains a polymer compound in theform of fine particles.
 8. The lithographic printing plate precursoraccording to claim 7, wherein the polymer compound in the form of fineparticles comprises a copolymer containing styrene and acrylonitrile. 9.The lithographic printing plate precursor according to claim 8, whereinthe polymer compound in the form of fine particles is a thermoplasticpolymer.
 10. A method of producing a lithographic printing plateprecursor which includes a support; and an image recording layer on thesupport, in which a region of a surface of the lithographic printingplate precursor at a side of the image recording layer, which is from anend portion of the lithographic printing plate precursor to a portioninside the end portion by 5 mm, contains at least one polymer selectedfrom: a polymer having an amide bond of the structure —NRC(═O)— in whichR represents a hydrogen atom or a substituent in a main chain or a graftchain and derivatives of the polymer; a polymer having a urethane bondof the structure —NRC(═O)O— in which R represents a hydrogen atom or asubstituent in a main chain or a graft chain and derivatives of thepolymer; a polymer having a urea bond of the structure —NRC(═O)NR— inwhich R represents a hydrogen atom or a substituent in a main chain or agraft chain and derivatives of the polymer; a polymer having an esterbond of the structure —C(═O)O— in a main chain or a graft chain andderivatives of the polymer; and a polymer having a carbonate bond of thestructure —OCOO— in a main chain or a graft chain and derivatives of thepolymer, and has a content of the polymer per unit area which is greaterthan a content of the polymer per unit area in a region other than theregion of a surface of the lithographic printing plate precursor at aside of the image recording layer by an amount of 10 mg/m² or greater,the method comprising: cutting the lithographic printing plateprecursor; and after the cutting, coating a part of the image recordinglayer with a coating solution containing the polymer.